@Override
        public CustomDefinition provideCustomSchemaDefinition(ResolvedType javaType, SchemaGenerationContext context) {
            if (javaType.isInstanceOf(Enum.class)) {
                ObjectNode customNode = context.getGeneratorConfig().createObjectNode()
                        .put(context.getKeyword(SchemaKeyword.TAG_TYPE), context.getKeyword(SchemaKeyword.TAG_TYPE_STRING));
                new AttributeCollector(context.getGeneratorConfig().getObjectMapper())
                        .setEnum(customNode, EnumModule.extractEnumValues(javaType, this.enumConstantToString), context);
                return new CustomDefinition(customNode);
            }
            return null;
        }
Constructor.

@param enumConstantToString how to derive a plain string representation from an enum constant value
jsonschema-generator/src/main/java/com/github/victools/jsonschema/generator/impl/module/EnumModule.java