Add missing underscores for PascalCase enum values #4837

Author: renatomameli

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

@@ -2039,7 +2039,7 @@ public String toEnumVarName(String value, String datatype) {
         }
 
         // string
-        String var = value.replaceAll("\\W+", "_").toUpperCase(Locale.ROOT);
+        String var = underscore(value.replaceAll("\\W+", "_")).toUpperCase(Locale.ROOT);
         if (var.matches("\\d.*")) {
             var = "_" + var;
         }

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

@@ -61,6 +61,13 @@ public void toEnumVarNameShouldNotResultInSingleUnderscore() throws Exception {
         Assert.assertEquals(fakeJavaCodegen.toEnumVarName("==", "String"), "u");
     }
 
+    @Test
+    public void toEnumVarNameAddUnderscoresIfValueIsPascalCase() {
+        Assert.assertEquals(fakeJavaCodegen.toEnumVarName("OnlyCamelCase", "String"), "ONLY_CAMEL_CASE");
+        Assert.assertEquals(fakeJavaCodegen.toEnumVarName("WithNumber1", "String"), "WITH_NUMBER1");
+        Assert.assertEquals(fakeJavaCodegen.toEnumVarName("_LeadingUnderscore", "String"), "_LEADING_UNDERSCORE");
+    }
+
     @Test
     public void toVarNameShouldAvoidOverloadingGetClassMethod() throws Exception {
         Assert.assertEquals(fakeJavaCodegen.toVarName("class"), "propertyClass");