diff --git a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/JavaClientCodegen.java b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/JavaClientCodegen.java
index 452936d3992..2bc9c5ef8cb 100644
--- a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/JavaClientCodegen.java
+++ b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/JavaClientCodegen.java
@@ -34,6 +34,7 @@ import org.slf4j.LoggerFactory;
 
 import java.io.File;
 import java.util.*;
+import java.util.regex.Matcher;
 import java.util.regex.Pattern;
 
 import static com.google.common.base.CaseFormat.LOWER_CAMEL;
@@ -623,8 +624,18 @@ public class JavaClientCodegen extends AbstractJavaCodegen
         if (FEIGN.equals(getLibrary())) {
             Map<String, Object> operations = (Map<String, Object>) objs.get("operations");
             List<CodegenOperation> operationList = (List<CodegenOperation>) operations.get("operation");
+            Pattern methodPattern = Pattern.compile("^(.*):([^:]*)$");
             for (CodegenOperation op : operationList) {
                 String path = op.path;
+                String method = "";
+
+                // if a custom method is found at the end of the path, cut it off for later
+                Matcher m = methodPattern.matcher(path);
+                if (m.find()) {
+                    path = m.group(1);
+                    method = m.group(2);
+                }
+
                 String[] items = path.split("/", -1);
 
                 for (int i = 0; i < items.length; ++i) {
@@ -634,6 +645,10 @@ public class JavaClientCodegen extends AbstractJavaCodegen
                     }
                 }
                 op.path = StringUtils.join(items, "/");
+                // Replace the custom method on the path if one was found earlier
+                if (!method.isEmpty()) {
+                    op.path += ":" + method;
+                }
             }
         }
 
diff --git a/modules/openapi-generator/src/test/java/org/openapitools/codegen/java/JavaClientCodegenTest.java b/modules/openapi-generator/src/test/java/org/openapitools/codegen/java/JavaClientCodegenTest.java
index 998267dc417..f5daa8e207e 100644
--- a/modules/openapi-generator/src/test/java/org/openapitools/codegen/java/JavaClientCodegenTest.java
+++ b/modules/openapi-generator/src/test/java/org/openapitools/codegen/java/JavaClientCodegenTest.java
@@ -1079,4 +1079,31 @@ public class JavaClientCodegenTest {
                 .filter(filter)
                 .findFirst();
     }
+
+    @Test
+    public void testCustomMethodParamsAreCamelizedWhenUsingFeign() throws IOException {
+
+        File output = Files.createTempDirectory("test").toFile();
+
+        final CodegenConfigurator configurator = new CodegenConfigurator()
+                .setGeneratorName("java")
+                .setLibrary(JavaClientCodegen.FEIGN)
+                .setInputSpec("src/test/resources/3_0/issue_7791.yaml")
+                .setOutputDir(output.getAbsolutePath().replace("\\", "/"));
+
+        final ClientOptInput clientOptInput = configurator.toClientOptInput();
+        DefaultGenerator generator = new DefaultGenerator();
+        List<File> files = generator.opts(clientOptInput).generate();
+
+        TestUtils.ensureContainsFile(files, output, "src/main/java/org/openapitools/client/api/DefaultApi.java");
+
+        validateJavaSourceFiles(files);
+
+        TestUtils.assertFileContains(Paths.get(output + "/src/main/java/org/openapitools/client/api/DefaultApi.java"),
+                "@RequestLine(\"POST /events/{eventId}:undelete\")");
+        TestUtils.assertFileNotContains(Paths.get(output + "/src/main/java/org/openapitools/client/api/DefaultApi.java"),
+                "event_id");
+
+        output.deleteOnExit();
+    }
 }
diff --git a/modules/openapi-generator/src/test/resources/3_0/issue_7791.yaml b/modules/openapi-generator/src/test/resources/3_0/issue_7791.yaml
new file mode 100644
index 00000000000..3065375ecc3
--- /dev/null
+++ b/modules/openapi-generator/src/test/resources/3_0/issue_7791.yaml
@@ -0,0 +1,20 @@
+openapi: 3.0.1
+info:
+  title: Custom methods
+  description: "Google custom methods syntax"
+  version: 0.0.1
+
+paths:
+  /events/{event_id}:undelete:
+    post:
+      operationId: undeleteOperation
+      parameters:
+        - name: event_id
+          in: path
+          required: true
+          description: Event Id
+          schema:
+            type: number
+      responses:
+        200:
+          description: success
\ No newline at end of file