[JAVA] [Bug] '$' character in enums is converted to '_' by swagger-codgen

Description

Hi,

I'm using swagger-codgen to generate code from OpenAPI yaml file.
When I generate models with enum containing dollar character '$', the '$' character is converted to underscore '_'

OpenAPI declaration file

openapi: 3.0.3
...
components:
	schemas:
		DocType:
		  type: string
		  description: Type of doc
		  enum:
			- TEST$1
			- TEST$2
			- TEST$3

Generation plugin in pom.xml

<plugin>
	<groupId>io.swagger.codegen.v3</groupId>
	<artifactId>swagger-codegen-maven-plugin</artifactId>
	<version>${io.swagger.codegen.v3.version}</version>
	<executions>
		<execution>
			<goals>
				<goal>generate</goal>
			</goals>
			<configuration>
				<inputSpec>${project.basedir}/openapi.yml</inputSpec>
				<language>spring</language>
				<modelPackage>com.he.model</modelPackage>
				<apiPackage>com.he.api</apiPackage>
				<supportingFilesToGenerate>ApiUtil.java</supportingFilesToGenerate>
				<configOptions>
					<dateLibrary>java8</dateLibrary>
					<delegatePattern>true</delegatePattern>
					<useTags>true</useTags>
					<unhandledException>true</unhandledException>
				</configOptions>
			</configuration>
		</execution>
	</executions>
</plugin>

Generated model

public enum DocType {
  TEST_1("TEST$1"),
    TEST_2("TEST$2"),
    TEST_3("TEST$3");

  private String value;

  DocType(String value) {
    this.value = value;
  }

  @Override
  @JsonValue
  public String toString() {
    return String.valueOf(value);
  }

  @JsonCreator
  public static DocType fromValue(String text) {
    for (DocType b : DocType.values()) {
      if (String.valueOf(b.value).equals(text)) {
        return b;
      }
    }
    return null;
  }
}

Swagger-codegen version

3.0.30

Command line used for generation

Generate code with mvn install

Reproduce the issue with the supplied OpenAPI declaration and Maven plugin configuration using mvn install. Inspect the generated DocType enum and trace the Java enum-name generation entry point or templates. Done means enum constants generated from values containing '$' remain distinct while preserving their original serialized values.