add method to return the title

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

@@ -8480,4 +8480,17 @@ public class DefaultCodegen implements CodegenConfig {
         }
         operation.hasParams = !operation.allParams.isEmpty();
     }
+
+    /**
+     * Returns the title in the info section of the spec or default to openapi if not defined.
+     *
+     * @return title
+     */
+    protected String getInfoTitle() {
+        if (openAPI.getInfo() != null) {
+            return openAPI.getInfo().getTitle();
+        } else {
+            return "openapi"; // default to openapi if title not set
+        }
+    }
 }

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

@@ -160,7 +160,7 @@ public class ApexClientCodegen extends AbstractApexCodegen {
 
     @Override
     public void preprocessOpenAPI(OpenAPI openAPI) {
-        String calloutLabel = openAPI.getInfo().getTitle();
+        String calloutLabel = getInfoTitle();
         if (StringUtils.isNotBlank(namedCredential)) {
             calloutLabel = namedCredential;
         }

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

@@ -550,7 +550,7 @@ public class HaskellHttpClientCodegen extends DefaultCodegen implements CodegenC
 
     @Override
     public void preprocessOpenAPI(OpenAPI openAPI) {
-        String baseTitle = openAPI.getInfo().getTitle();
+        String baseTitle = getInfoTitle();
 
         if (StringUtils.isBlank(baseTitle)) {
             baseTitle = "OpenAPI";

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

@@ -275,7 +275,7 @@ public class HaskellServantCodegen extends DefaultCodegen implements CodegenConf
     @Override
     public void preprocessOpenAPI(OpenAPI openAPI) {
         // From the title, compute a reasonable name for the package and the API
-        String title = openAPI.getInfo().getTitle();
+        String title = getInfoTitle();
 
         // Drop any API suffix
         if (title == null) {

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

@@ -471,7 +471,7 @@ public class JavaPKMSTServerCodegen extends AbstractJavaCodegen {
         if (!additionalProperties.containsKey(TITLE)) {
             // From the title, compute a reasonable name for the package and the
             // API
-            String title = openAPI.getInfo().getTitle();
+            String title = getInfoTitle();
 
             // Drop any API suffix
             if (title != null) {

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

@@ -771,7 +771,7 @@ public class KotlinSpringServerCodegen extends AbstractKotlinCodegen
             // This is an additional step we add when pre-processing the API spec, if
             // there is no user configuration set for the `title` of the project,
             // we try build and normalise a title from the API spec itself.
-            String title = openAPI.getInfo().getTitle();
+            String title = getInfoTitle();
 
             // Drop any API suffix
             if (title != null) {

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

@@ -689,7 +689,7 @@ public class SpringCodegen extends AbstractJavaCodegen
 
         if (!additionalProperties.containsKey(TITLE)) {
             // From the title, compute a reasonable name for the package and the API
-            String title = openAPI.getInfo().getTitle();
+            String title = getInfoTitle();
 
             // Drop any API suffix
             if (title != null) {

modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/StaticHtml2Generator.java

@@ -230,7 +230,7 @@ public class StaticHtml2Generator extends DefaultCodegen implements CodegenConfi
             Markdown markInstance = new Markdown();
             openAPI.getInfo().setDescription(markInstance.toHtml(currentDescription));
         } else {
-            LOGGER.error("OpenAPI object description is empty [{}]", openAPI.getInfo().getTitle());
+            LOGGER.error("OpenAPI object description is empty [{}]", getInfoTitle());
         }
     }