Add openapiGeneratorIgnoreList option to pre-populate .openapi-generator-ignore (#17164)

* add openapiGeneratorIgnoreList option to pre-populate .openapi-generator-ignore

* minor fix

* better code format

* add tests

docs/customization.md

@@ -266,6 +266,11 @@ Upon first code generation, you may also pass the CLI option `--ignore-file-over
 
 Editor support for `.openapi-generator-ignore` files is available in IntelliJ via the [.ignore plugin](https://plugins.jetbrains.com/plugin/7495--ignore).
 
+One may want to pre-populate `.openapi-generator-ignore` with a list of entries during the code generation process and the global/general option `openapiGeneatorIgnoreList` (e.g. --openapi-generator-ignore-list in CLI) can do exactly that. For example,
+```
+java -jar modules/openapi-generator-cli/target/openapi-generator-cli.jar generate -g spring -i modules/openapi-generator/src/test/resources/3_0/petstore.yaml -o /tmp/spring --additional-properties useTags=true --openapi-generator-ignore-list "README.md,pom.xml,docs/*.md,src/main/java/org/openapitools/model/*"
+```
+
 ## Customizing the generator
 
 There are different aspects of customizing the code generator beyond just creating or modifying templates.  Each language has a supporting configuration file to handle different type mappings, etc:

modules/openapi-generator-cli/src/main/java/org/openapitools/codegen/cmd/ConfigHelp.java

@@ -101,6 +101,9 @@ public class ConfigHelp extends OpenApiGeneratorCommand {
     @Option(name = {"--language-specific-primitive"}, title = "language specific primitives", description = "displays the language specific primitives (types which require no additional imports, or which may conflict with user defined model names)")
     private Boolean languageSpecificPrimitives;
 
+    @Option(name = {"--openapi-generator-ignore-list"}, title = "openapi generator ignore list", description = "displays the openapi generator ignore list")
+    private Boolean openapiGeneratorIgnoreList;
+
     @Option(name = {"--reserved-words"}, title = "language specific reserved words", description = "displays the reserved words which may result in renamed model or property names")
     private Boolean reservedWords;
 
@@ -588,6 +591,13 @@ public class ConfigHelp extends OpenApiGeneratorCommand {
             sb.append(newline);
         }
 
+        if (Boolean.TRUE.equals(openapiGeneratorIgnoreList)) {
+            sb.append(newline).append("OPENAPI GENERATOR IGNORE LIST").append(newline).append(newline);
+            String[] arr = config.openapiGeneratorIgnoreList().stream().sorted().toArray(String[]::new);
+            writePlainTextFromArray(sb, arr, optIndent);
+            sb.append(newline);
+        }
+
         if (Boolean.TRUE.equals(reservedWords)) {
             sb.append(newline).append("RESERVED WORDS").append(newline).append(newline);
             String[] arr = config.reservedWords().stream().sorted().toArray(String[]::new);

modules/openapi-generator-cli/src/main/java/org/openapitools/codegen/cmd/Generate.java

@@ -160,6 +160,13 @@ public class Generate extends OpenApiGeneratorCommand {
                     + " You can also have multiple occurrences of this option.")
     private List<String> languageSpecificPrimitives = new ArrayList<>();
 
+    @Option(
+            name = {"--openapi-generator-ignore-list"},
+            title = ".openapi-generaotr-ignore list",
+            description = "specifies entries in the .openapi-generator-ignore file relative/path/to/file1,relative/path/to/file2. For example: README.md,pom.xml"
+                    + " You can also have multiple occurrences of this option.")
+    private List<String> openapiGeneratorIgnoreList = new ArrayList<>();
+
     @Option(
             name = {"--import-mappings"},
             title = "import mappings",
@@ -504,6 +511,7 @@ public class Generate extends OpenApiGeneratorCommand {
         applyTypeMappingsKvpList(typeMappings, configurator);
         applyAdditionalPropertiesKvpList(additionalProperties, configurator);
         applyLanguageSpecificPrimitivesCsvList(languageSpecificPrimitives, configurator);
+        applyOpenAPIGeneratorIgnoreListCsvList(openapiGeneratorIgnoreList, configurator);
         applyReservedWordsMappingsKvpList(reservedWordsMappings, configurator);
         applyServerVariablesKvpList(serverVariableOverrides, configurator);
 

modules/openapi-generator-core/src/main/java/org/openapitools/codegen/config/GeneratorSettings.java

@@ -59,6 +59,7 @@ public final class GeneratorSettings implements Serializable {
     private final Map<String, String> enumNameMappings;
     private final Map<String, String> openapiNormalizer;
     private final Set<String> languageSpecificPrimitives;
+    private final Set<String> openapiGeneratorIgnoreList;
     private final Map<String, String> reservedWordsMappings;
     private final Map<String, String> serverVariables;
 
@@ -330,6 +331,15 @@ public final class GeneratorSettings implements Serializable {
         return languageSpecificPrimitives;
     }
 
+    /**
+     * Gets openapi generator ignore list.
+     *
+     * @return the openapi generator ignore list
+     */
+    public Set<String> getOpenAPIGeneratorIgnoreList() {
+        return openapiGeneratorIgnoreList;
+    }
+
     /**
      * Gets reserved word mappings. Values defined here define how a reserved word should be escaped.
      * <p>
@@ -438,6 +448,7 @@ public final class GeneratorSettings implements Serializable {
         enumNameMappings = Collections.unmodifiableMap(builder.enumNameMappings);
         openapiNormalizer = Collections.unmodifiableMap(builder.openapiNormalizer);
         languageSpecificPrimitives = Collections.unmodifiableSet(builder.languageSpecificPrimitives);
+        openapiGeneratorIgnoreList = Collections.unmodifiableSet(builder.openapiGeneratorIgnoreList);
         reservedWordsMappings = Collections.unmodifiableMap(builder.reservedWordsMappings);
         serverVariables = Collections.unmodifiableMap(builder.serverVariables);
         gitHost = builder.gitHost;
@@ -516,6 +527,7 @@ public final class GeneratorSettings implements Serializable {
         enumNameMappings = Collections.unmodifiableMap(new HashMap<>(0));
         openapiNormalizer = Collections.unmodifiableMap(new HashMap<>(0));
         languageSpecificPrimitives = Collections.unmodifiableSet(new HashSet<>(0));
+        openapiGeneratorIgnoreList = Collections.unmodifiableSet(new HashSet<>(0));
         reservedWordsMappings = Collections.unmodifiableMap(new HashMap<>(0));
         serverVariables = Collections.unmodifiableMap(new HashMap<>(0));
     }
@@ -593,6 +605,9 @@ public final class GeneratorSettings implements Serializable {
         if (copy.getLanguageSpecificPrimitives() != null) {
             builder.languageSpecificPrimitives.addAll(copy.getLanguageSpecificPrimitives());
         }
+        if (copy.getOpenAPIGeneratorIgnoreList() != null) {
+            builder.openapiGeneratorIgnoreList.addAll(copy.getOpenAPIGeneratorIgnoreList());
+        }
         if (copy.getReservedWordsMappings() != null) {
             builder.reservedWordsMappings.putAll(copy.getReservedWordsMappings());
         }
@@ -638,6 +653,7 @@ public final class GeneratorSettings implements Serializable {
         private Map<String, String> enumNameMappings;
         private Map<String, String> openapiNormalizer;
         private Set<String> languageSpecificPrimitives;
+        private Set<String> openapiGeneratorIgnoreList;
         private Map<String, String> reservedWordsMappings;
         private Map<String, String> serverVariables;
         private String gitHost;
@@ -663,6 +679,7 @@ public final class GeneratorSettings implements Serializable {
             enumNameMappings = new HashMap<>();
             openapiNormalizer = new HashMap<>();
             languageSpecificPrimitives = new HashSet<>();
+            openapiGeneratorIgnoreList = new HashSet<>();
             reservedWordsMappings = new HashMap<>();
             serverVariables = new HashMap<>();
 
@@ -1137,6 +1154,31 @@ public final class GeneratorSettings implements Serializable {
             return this;
         }
 
+        /**
+         * Sets the {@code openapiGeneratorIgnoreList} and returns a reference to this Builder so that the methods can be chained together.
+         *
+         * @param openapiGeneratorIgnoreList the {@code openapiGeneratorIgnoreList} to set
+         * @return a reference to this Builder
+         */
+        public Builder withOpenAPIGeneratorIgnoreList(Set<String> openapiGeneratorIgnoreList) {
+            this.openapiGeneratorIgnoreList = openapiGeneratorIgnoreList;
+            return this;
+        }
+
+        /**
+         * Sets a single {@code openapiGeneratorIgnoreList} and returns a reference to this Builder so that the methods can be chained together.
+         *
+         * @param value The value of entry to set
+         * @return a reference to this Builder
+         */
+        public Builder withOpenAPIGeneratorIgnoreList(String value) {
+            if (this.openapiGeneratorIgnoreList == null) {
+                this.openapiGeneratorIgnoreList = new HashSet<>();
+            }
+            this.openapiGeneratorIgnoreList.add(value);
+            return this;
+        }
+
         /**
          * Sets the {@code reservedWordsMappings} and returns a reference to this Builder so that the methods can be chained together.
          *
@@ -1266,6 +1308,7 @@ public final class GeneratorSettings implements Serializable {
                 ", additionalProperties=" + additionalProperties +
                 ", importMappings=" + importMappings +
                 ", languageSpecificPrimitives=" + languageSpecificPrimitives +
+                ", openapiGeneratorIgnoreList=" + openapiGeneratorIgnoreList +
                 ", reservedWordsMappings=" + reservedWordsMappings +
                 ", gitHost='" + gitHost + '\'' +
                 ", gitUserId='" + gitUserId + '\'' +
@@ -1305,6 +1348,7 @@ public final class GeneratorSettings implements Serializable {
                 Objects.equals(getEnumNameMappings(), that.getEnumNameMappings()) &&
                 Objects.equals(getOpenAPINormalizer(), that.getOpenAPINormalizer()) &&
                 Objects.equals(getLanguageSpecificPrimitives(), that.getLanguageSpecificPrimitives()) &&
+                Objects.equals(getOpenAPIGeneratorIgnoreList(), that.getOpenAPIGeneratorIgnoreList()) &&
                 Objects.equals(getReservedWordsMappings(), that.getReservedWordsMappings()) &&
                 Objects.equals(getGitHost(), that.getGitHost()) &&
                 Objects.equals(getGitUserId(), that.getGitUserId()) &&
@@ -1341,6 +1385,7 @@ public final class GeneratorSettings implements Serializable {
                 getEnumNameMappings(),
                 getOpenAPINormalizer(),
                 getLanguageSpecificPrimitives(),
+                getOpenAPIGeneratorIgnoreList(),
                 getReservedWordsMappings(),
                 getGitHost(),
                 getGitUserId(),

modules/openapi-generator-gradle-plugin/src/main/kotlin/org/openapitools/generator/gradle/plugin/extensions/OpenApiGeneratorGenerateExtension.kt

@@ -147,6 +147,11 @@ open class OpenApiGeneratorGenerateExtension(project: Project) {
      */
     val languageSpecificPrimitives = project.objects.listProperty<String>()
 
+    /**
+     * Specifies .openapi-generator-ignore list in the form of relative/path/to/file1,relative/path/to/file2. For example: README.md,pom.xml. 
+     */
+    val openapiGeneratorIgnoreList = project.objects.listProperty<String>()
+
     /**
      * Specifies mappings between a given class and the import that should be used for that class.
      */

modules/openapi-generator-gradle-plugin/src/main/kotlin/org/openapitools/generator/gradle/plugin/tasks/GenerateTask.kt

@@ -244,6 +244,13 @@ open class GenerateTask @Inject constructor(private val objectFactory: ObjectFac
     @Input
     val languageSpecificPrimitives = project.objects.listProperty<String>()
 
+    /**
+     * Specifies .openapi-generator-ignore list in the form of relative/path/to/file1,relative/path/to/file2. For example: README.md,pom.xml.
+     */
+    @Optional
+    @Input
+    val openapiGeneratorIgnoreList = project.objects.listProperty<String>()
+
     /**
      * Specifies mappings between a given class and the import that should be used for that class.
      */
@@ -895,6 +902,12 @@ open class GenerateTask @Inject constructor(private val objectFactory: ObjectFac
                 }
             }
 
+            if (openapiGeneratorIgnoreList.isPresent) {
+                openapiGeneratorIgnoreList.get().forEach {
+                    configurator.addOpenAPIGeneratorIgnoreList(it)
+                }
+            }
+
             if (reservedWordsMappings.isPresent) {
                 reservedWordsMappings.get().forEach { entry ->
                     configurator.addAdditionalReservedWordMapping(entry.key, entry.value)

modules/openapi-generator-maven-plugin/src/main/java/org/openapitools/codegen/plugin/CodeGenMojo.java

@@ -374,6 +374,12 @@ public class CodeGenMojo extends AbstractMojo {
     @Parameter(name = "languageSpecificPrimitives", property = "openapi.generator.maven.plugin.languageSpecificPrimitives")
     private List<String> languageSpecificPrimitives;
 
+    /**
+     * A list of openapi-generator-ignore entries
+     */
+    @Parameter(name = "openapiGeneratorIgnoreList", property = "openapi.generator.maven.plugin.openapiGeneratorIgnoreList")
+    private List<String> openapiGeneratorIgnoreList;
+
     /**
      * A map of additional properties that can be referenced by the mustache templates
      */
@@ -783,6 +789,12 @@ public class CodeGenMojo extends AbstractMojo {
                             .get("language-specific-primitives").toString(), configurator);
                 }
 
+                // Retained for backwards-compatibility with configOptions -> openapi-generator-ignore-list
+                if (openapiGeneratorIgnoreList == null && configOptions.containsKey("openapi-generator-ignore-list")) {
+                    applyOpenAPIGeneratorIgnoreListCsv(configOptions
+                            .get("openapi-generator-ignore-list").toString(), configurator);
+                }
+
                 // Retained for backwards-compatibility with configOptions -> additional-properties
                 if (additionalProperties == null && configOptions.containsKey("additional-properties")) {
                     applyAdditionalPropertiesKvp(configOptions.get("additional-properties").toString(),
@@ -861,6 +873,12 @@ public class CodeGenMojo extends AbstractMojo {
                 applyLanguageSpecificPrimitivesCsvList(languageSpecificPrimitives, configurator);
             }
 
+            // Apply Language Specific Primitives
+            if (openapiGeneratorIgnoreList != null
+                    && (configOptions == null || !configOptions.containsKey("openapi-generator-ignore-list"))) {
+                applyOpenAPIGeneratorIgnoreListCsvList(openapiGeneratorIgnoreList, configurator);
+            }
+
             // Apply Additional Properties
             if (additionalProperties != null && (configOptions == null || !configOptions.containsKey("additional-properties"))) {
                 applyAdditionalPropertiesKvpList(additionalProperties, configurator);

modules/openapi-generator/src/main/java/org/openapitools/codegen/CodegenConfig.java

@@ -173,6 +173,8 @@ public interface CodegenConfig {
 
     Set<String> languageSpecificPrimitives();
 
+    Set<String> openapiGeneratorIgnoreList();
+
     Map<String, String> reservedWordsMappings();
 
     void preprocessOpenAPI(OpenAPI openAPI);
@@ -349,4 +351,6 @@ public interface CodegenConfig {
 
     boolean getUseOpenAPINormalizer();
 
+    Set<String> getOpenAPIGeneratorIgnoreList();
+
 }

modules/openapi-generator/src/main/java/org/openapitools/codegen/DefaultCodegen.java

@@ -160,6 +160,7 @@ public class DefaultCodegen implements CodegenConfig {
     protected Map<String, String> instantiationTypes;
     protected Set<String> reservedWords;
     protected Set<String> languageSpecificPrimitives = new HashSet<>();
+    protected Set<String> openapiGeneratorIgnoreList = new HashSet<>();
     protected Map<String, String> importMapping = new HashMap<>();
     // a map to store the mapping between a schema and the new one
     protected Map<String, String> schemaMapping = new HashMap<>();
@@ -1211,6 +1212,11 @@ public class DefaultCodegen implements CodegenConfig {
         return languageSpecificPrimitives;
     }
 
+    @Override
+    public Set<String> openapiGeneratorIgnoreList() {
+        return openapiGeneratorIgnoreList;
+    }
+
     @Override
     public Map<String, String> importMapping() {
         return importMapping;
@@ -8317,6 +8323,11 @@ public class DefaultCodegen implements CodegenConfig {
     @Override
     public boolean getUseOpenAPINormalizer() { return true; }
 
+    @Override
+    public Set<String> getOpenAPIGeneratorIgnoreList() {
+        return openapiGeneratorIgnoreList;
+    }
+
     /*
     A function to convert yaml or json ingested strings like property names
     And convert special characters like newline, tab, carriage return

modules/openapi-generator/src/main/java/org/openapitools/codegen/DefaultGenerator.java

@@ -36,12 +36,10 @@ import org.apache.commons.lang3.StringUtils;
 import org.openapitools.codegen.api.TemplateDefinition;
 import org.openapitools.codegen.api.TemplatePathLocator;
 import org.openapitools.codegen.api.TemplateProcessor;
-import org.openapitools.codegen.config.GeneratorSettings;
 import org.openapitools.codegen.config.GlobalSettings;
 import org.openapitools.codegen.api.TemplatingEngineAdapter;
 import org.openapitools.codegen.api.TemplateFileType;
 import org.openapitools.codegen.ignore.CodegenIgnoreProcessor;
-import org.openapitools.codegen.languages.CSharpClientCodegen;
 import org.openapitools.codegen.meta.GeneratorMetadata;
 import org.openapitools.codegen.meta.Stability;
 import org.openapitools.codegen.model.ApiInfoMap;
@@ -65,6 +63,7 @@ import org.slf4j.LoggerFactory;
 import java.io.*;
 import java.net.URL;
 import java.nio.charset.StandardCharsets;
+import java.nio.file.Files;
 import java.nio.file.Path;
 import java.time.ZonedDateTime;
 import java.util.*;
@@ -701,17 +700,17 @@ public class DefaultGenerator implements Generator {
                         String outputDir = config.getOutputDir() + File.separator + config.templateOutputDirs().get(templateName);
                         String filename = config.apiFilename(templateName, tag, outputDir);
                         // do not overwrite apiController file for spring server
-                        if (apiFilePreCheck(filename, generatorCheck, templateName, templateCheck)){
+                        if (apiFilePreCheck(filename, generatorCheck, templateName, templateCheck)) {
                             written = processTemplateToFile(operation, templateName, filename, generateApis, CodegenConstants.APIS, outputDir);
                         } else {
-                            LOGGER.info("Implementation file {} is not overwritten",filename);
+                            LOGGER.info("Implementation file {} is not overwritten", filename);
                         }
                     } else {
                         String filename = config.apiFilename(templateName, tag);
-                        if(apiFilePreCheck(filename, generatorCheck, templateName, templateCheck)){
+                        if (apiFilePreCheck(filename, generatorCheck, templateName, templateCheck)) {
                             written = processTemplateToFile(operation, templateName, filename, generateApis, CodegenConstants.APIS);
                         } else {
-                            LOGGER.info("Implementation file {} is not overwritten",filename);
+                            LOGGER.info("Implementation file {} is not overwritten", filename);
                         }
                     }
                     if (written != null) {
@@ -764,17 +763,83 @@ public class DefaultGenerator implements Generator {
     }
 
     // checking if apiController file is already existed for spring generator
-    private boolean apiFilePreCheck(String filename, String generator, String templateName, String apiControllerTemplate){
+    private boolean apiFilePreCheck(String filename, String generator, String templateName, String apiControllerTemplate) {
         File apiFile = new File(filename);
         return !(apiFile.exists() && config.getName().equals(generator) && templateName.equals(apiControllerTemplate));
     }
 
+    /*
+     * Generate .openapi-generator-ignore if the option openapiGeneratorIgnoreFile is enabled.
+     */
+    private void generateOpenAPIGeneratorIgnoreFile() {
+        if (config.getOpenAPIGeneratorIgnoreList() == null || config.getOpenAPIGeneratorIgnoreList().isEmpty()) {
+            return;
+        }
+
+        final String openapiGeneratorIgnore = ".openapi-generator-ignore";
+        String ignoreFileNameTarget = config.outputFolder() + File.separator + openapiGeneratorIgnore;
+        File ignoreFile = new File(ignoreFileNameTarget);
+        // use the entries provided by the users to pre-populate .openapi-generator-ignore
+        try {
+            LOGGER.info("Writing file " + ignoreFileNameTarget + " (which is always overwritten when the option `openapiGeneratorIgnoreFile` is enabled.)");
+            new File(config.outputFolder()).mkdirs();
+            ignoreFile.createNewFile();
+            String header = String.join("\n",
+                    "# IMPORTANT: this file is generated with the option `openapiGeneratorIgnoreList` enabled",
+                    "# (--openapi-generator-ignore-list in CLI for example) so the entries below are pre-populated based",
+                    "# on the input provided by the users and this file will be overwritten every time when the option is",
+                    "# enabled (which is the exact opposite of the default behaviour to not overwrite",
+                    "# .openapi-generator-ignore if the file exists).",
+                    "",
+                    "# OpenAPI Generator Ignore",
+                    "# Generated by openapi-generator https://github.com/openapitools/openapi-generator",
+                    "",
+                    "# Use this file to prevent files from being overwritten by the generator.",
+                    "# The patterns follow closely to .gitignore or .dockerignore.",
+                    "",
+                    "# As an example, the C# client generator defines ApiClient.cs.",
+                    "# You can make changes and tell OpenAPI Generator to ignore just this file by uncommenting the following line:",
+                    "#ApiClient.cs",
+                    "",
+                    "# You can match any string of characters against a directory, file or extension with a single asterisk (*):",
+                    "#foo/*/qux",
+                    "# The above matches foo/bar/qux and foo/baz/qux, but not foo/bar/baz/qux",
+                    "",
+                    "# You can recursively match patterns against a directory, file or extension with a double asterisk (**):",
+                    "#foo/**/qux",
+                    "# This matches foo/bar/qux, foo/baz/qux, and foo/bar/baz/qux",
+                    "",
+                    "# You can also negate patterns with an exclamation (!).",
+                    "# For example, you can ignore all files in a docs folder with the file extension .md:",
+                    "#docs/*.md",
+                    "# Then explicitly reverse the ignore rule for a single file:",
+                    "#!docs/README.md",
+                    "",
+                    "# The following entries are pre-populated based on the input obtained via",
+                    "# the option `openapiGeneratorIgnoreList` (--openapi-generator-ignore-list in CLI for example).",
+                    "");
+            Writer fileWriter = Files.newBufferedWriter(ignoreFile.toPath(), StandardCharsets.UTF_8);
+            fileWriter.write(header);
+            // add entries provided by the users
+            for (String entry : config.getOpenAPIGeneratorIgnoreList()) {
+                fileWriter.write(entry);
+                fileWriter.write("\n");
+            }
+            fileWriter.close();
+            // re-create ignore processor based on the newly-created .openapi-generator-ignore
+            this.ignoreProcessor = new CodegenIgnoreProcessor(ignoreFile);
+        } catch (IOException e) {
+            throw new RuntimeException("Failed to generate .openapi-generator-ignore when the option `openapiGeneratorIgnoreList` is enabled: ", e);
+        }
+    }
+
     private void generateSupportingFiles(List<File> files, Map<String, Object> bundle) {
         if (!generateSupportingFiles) {
             // TODO: process these anyway and report via dryRun?
             LOGGER.info("Skipping generation of supporting files.");
             return;
         }
+
         Set<String> supportingFilesToGenerate = null;
         String supportingFiles = GlobalSettings.getProperty(CodegenConstants.SUPPORTING_FILES);
         if (supportingFiles != null && !supportingFiles.isEmpty()) {
@@ -819,27 +884,30 @@ public class DefaultGenerator implements Generator {
 
         // Consider .openapi-generator-ignore a supporting file
         // Output .openapi-generator-ignore if it doesn't exist and wasn't explicitly created by a generator
-        final String openapiGeneratorIgnore = ".openapi-generator-ignore";
+        // and the option openapiGeneratorIgnoreList is not set
-        String ignoreFileNameTarget = config.outputFolder() + File.separator + openapiGeneratorIgnore;
+        if (config.openapiGeneratorIgnoreList() == null || config.openapiGeneratorIgnoreList().isEmpty()) {
-        File ignoreFile = new File(ignoreFileNameTarget);
+            final String openapiGeneratorIgnore = ".openapi-generator-ignore";
-        if (generateMetadata) {
+            String ignoreFileNameTarget = config.outputFolder() + File.separator + openapiGeneratorIgnore;
-            try {
+            File ignoreFile = new File(ignoreFileNameTarget);
-                boolean shouldGenerate = !ignoreFile.exists();
+            if (generateMetadata) {
-                if (shouldGenerate && supportingFilesToGenerate != null && !supportingFilesToGenerate.isEmpty()) {
+                try {
-                    shouldGenerate = supportingFilesToGenerate.contains(openapiGeneratorIgnore);
+                    boolean shouldGenerate = !ignoreFile.exists();
-                }
+                    if (shouldGenerate && supportingFilesToGenerate != null && !supportingFilesToGenerate.isEmpty()) {
-                File written = processTemplateToFile(bundle, openapiGeneratorIgnore, ignoreFileNameTarget, shouldGenerate, CodegenConstants.SUPPORTING_FILES);
+                        shouldGenerate = supportingFilesToGenerate.contains(openapiGeneratorIgnore);
-                if (written != null) {
-                    files.add(written);
-                    if (config.isEnablePostProcessFile() && !dryRun) {
-                        config.postProcessFile(written, "openapi-generator-ignore");
                     }
+                    File written = processTemplateToFile(bundle, openapiGeneratorIgnore, ignoreFileNameTarget, shouldGenerate, CodegenConstants.SUPPORTING_FILES);
+                    if (written != null) {
+                        files.add(written);
+                        if (config.isEnablePostProcessFile() && !dryRun) {
+                            config.postProcessFile(written, "openapi-generator-ignore");
+                        }
+                    }
+                } catch (Exception e) {
+                    throw new RuntimeException("Could not generate supporting file '" + ignoreFileNameTarget + "'", e);
                 }
-            } catch (Exception e) {
+            } else {
-                throw new RuntimeException("Could not generate supporting file '" + ignoreFileNameTarget + "'", e);
+                this.templateProcessor.skip(ignoreFile.toPath(), "Skipped by generateMetadata option supplied by user.");
             }
-        } else {
-            this.templateProcessor.skip(ignoreFile.toPath(), "Skipped by generateMetadata option supplied by user.");
         }
 
         generateVersionMetadata(files);
@@ -984,6 +1052,9 @@ public class DefaultGenerator implements Generator {
 
         processUserDefinedTemplates();
 
+        // generate .openapi-generator-ignore if the option openapiGeneratorIgnoreFile is enabled
+        generateOpenAPIGeneratorIgnoreFile();
+
         List<File> files = new ArrayList<>();
         // models
         List<String> filteredSchemas = ModelUtils.getSchemasUsedOnlyInFormParam(openAPI);

modules/openapi-generator/src/main/java/org/openapitools/codegen/config/CodegenConfigurator.java

@@ -77,6 +77,7 @@ public class CodegenConfigurator {
     private Map<String, String> enumNameMappings = new HashMap<>();
     private Map<String, String> openapiNormalizer = new HashMap<>();
     private Set<String> languageSpecificPrimitives = new HashSet<>();
+    private Set<String> openapiGeneratorIgnoreList = new HashSet<>();
     private Map<String, String> reservedWordsMappings = new HashMap<>();
     private Map<String, String> serverVariables = new HashMap<>();
     private String auth;
@@ -146,6 +147,9 @@ public class CodegenConfigurator {
             if(generatorSettings.getLanguageSpecificPrimitives() != null) {
                 configurator.languageSpecificPrimitives.addAll(generatorSettings.getLanguageSpecificPrimitives());
             }
+            if(generatorSettings.getOpenAPIGeneratorIgnoreList() != null) {
+                configurator.openapiGeneratorIgnoreList.addAll(generatorSettings.getOpenAPIGeneratorIgnoreList());
+            }
             if(generatorSettings.getReservedWordsMappings() != null) {
                 configurator.reservedWordsMappings.putAll(generatorSettings.getReservedWordsMappings());
             }
@@ -272,6 +276,12 @@ public class CodegenConfigurator {
         return this;
     }
 
+    public CodegenConfigurator addOpenAPIGeneratorIgnoreList(String value) {
+        this.openapiGeneratorIgnoreList.add(value);
+        generatorSettingsBuilder.withOpenAPIGeneratorIgnoreList(value);
+        return this;
+    }
+
     public CodegenConfigurator addGlobalProperty(String key, String value) {
         this.globalProperties.put(key, value);
         workflowSettingsBuilder.withGlobalProperty(key, value);
@@ -489,6 +499,13 @@ public class CodegenConfigurator {
         return this;
     }
 
+    public CodegenConfigurator setOpenAPIGeneratorIgnoreList(
+            Set<String> openapiGeneratorIgnoreList) {
+        this.openapiGeneratorIgnoreList = openapiGeneratorIgnoreList;
+        generatorSettingsBuilder.withOpenAPIGeneratorIgnoreList(openapiGeneratorIgnoreList);
+        return this;
+    }
+
     public CodegenConfigurator setLibrary(String library) {
         generatorSettingsBuilder.withLibrary(library);
         return this;
@@ -747,6 +764,7 @@ public class CodegenConfigurator {
         config.enumNameMapping().putAll(generatorSettings.getEnumNameMappings());
         config.openapiNormalizer().putAll(generatorSettings.getOpenAPINormalizer());
         config.languageSpecificPrimitives().addAll(generatorSettings.getLanguageSpecificPrimitives());
+        config.openapiGeneratorIgnoreList().addAll(generatorSettings.getOpenAPIGeneratorIgnoreList());
         config.reservedWordsMappings().putAll(generatorSettings.getReservedWordsMappings());
         config.additionalProperties().putAll(generatorSettings.getAdditionalProperties());
 

modules/openapi-generator/src/main/java/org/openapitools/codegen/config/CodegenConfiguratorUtils.java

@@ -237,6 +237,19 @@ public final class CodegenConfiguratorUtils {
         }
     }
 
+    public static void applyOpenAPIGeneratorIgnoreListCsvList(List<String> openapiGeneratorIgnoreList, CodegenConfigurator configurator) {
+        for (String propString : openapiGeneratorIgnoreList) {
+            applyOpenAPIGeneratorIgnoreListCsv(propString, configurator);
+        }
+    }
+
+    public static void applyOpenAPIGeneratorIgnoreListCsv(String openapiGeneratorIgnoreList, CodegenConfigurator configurator) {
+        final Set<String> set = createSetFromCsvList(openapiGeneratorIgnoreList);
+        for (String item : set) {
+            configurator.addOpenAPIGeneratorIgnoreList(item);
+        }
+    }
+
     public static void applyReservedWordsMappingsKvpList(List<String> reservedWordsMappings, CodegenConfigurator configurator) {
         for (String propString : reservedWordsMappings) {
             applyReservedWordsMappingsKvp(propString, configurator);

modules/openapi-generator/src/test/java/org/openapitools/codegen/java/JavaClientCodegenTest.java

@@ -2722,4 +2722,28 @@ public class JavaClientCodegenTest {
         File apiFile = files.get("AllOfDatetime.java");
         assertEquals(apiFile, null);
     }
+
+    @Test
+    public void testOpenAPIGeneratorIgnoreListOption() throws IOException {
+        File output = Files.createTempDirectory("openapi_generator_ignore_list_test_folder").toFile().getCanonicalFile();
+        output.deleteOnExit();
+        final OpenAPI openAPI = TestUtils.parseFlattenSpec("src/test/resources/3_0/allof_primitive.yaml");
+        final DefaultGenerator defaultGenerator = new DefaultGenerator();
+        final ClientOptInput clientOptInput = new ClientOptInput();
+        clientOptInput.openAPI(openAPI);
+        JavaClientCodegen javaClientCodegen = new JavaClientCodegen();
+        javaClientCodegen.setOutputDir(output.getAbsolutePath());
+        javaClientCodegen.setAutosetConstants(true);
+        javaClientCodegen.openapiGeneratorIgnoreList().add("README.md");
+        javaClientCodegen.openapiGeneratorIgnoreList().add("pom.xml");
+        clientOptInput.config(javaClientCodegen);
+        defaultGenerator.opts(clientOptInput);
+
+        Map<String, File> files = defaultGenerator.generate().stream()
+                .collect(Collectors.toMap(File::getName, Function.identity()));
+
+        // make sure README.md and pom.xml are not generated
+        assertEquals(files.get("README.md"), null);
+        assertEquals(files.get("pom.xml"), null);
+    }
 }