[JAXRS-SPEC] Enum values are generating """, "&#3D;", imports are being written inside class declaration

Description

I wanted to generate API Definition with the swagger-codegen-maven-plugin, for jaxrs-spec so that I receive only the models and basic API implementations (i.e., no factories). For all models that have an enum however, it produces uncompilable source code.

Swagger-codegen version

The latest stable build, 2.2.1, although I have also tried 2.2.2-SNAPSHOT but it has not made a difference.

Swagger declaration file content or url

  T:
    required:
      - a
      - c
    properties:
      a:
        type: number
        format: double
      c:
        type: string
      state: 
        type: string
        enum:
          - initial

Command line used for generation

mvn clean io.swagger:swagger-codegen-maven-plugin:generate with the following plugin entry in the pom.xml:

            <plugin>
                <groupId>io.swagger</groupId>
                <artifactId>swagger-codegen-maven-plugin</artifactId>
                <version>2.2.1</version>
                <configuration>
                    <inputSpec>${project.basedir}/src/main/resources/api.yaml</inputSpec>
                    <language>jaxrs-spec</language>
                    <output>${project.build.directory}/generated-sources/payment</output>
                    <configOptions>
                        <sourceFolder>src/java/main</sourceFolder>
                        <dateLibrary>java8</dateLibrary>
                    </configOptions>
                    <groupId>com.product</groupId>
                    <artifactId>rest</artifactId>
                    <modelPackage>com.product.rest.model</modelPackage>
                    <invokerPackage>com.product.rest.invoker</invokerPackage>
                    <apiPackage>com.product.rest.api</apiPackage>
                </configuration>
                <executions>
                    <execution>
                        <id>generate-server-stubs</id>
                        <goals>
                            <goal>generate</goal>
                        </goals>
                        <configuration>
                        </configuration>
                    </execution>
                </executions>
            </plugin>

Steps to reproduce

Attempt to generate server stubs using the model definition above.

The generated source code then looks similar to the following:

package com.product.rest.model;

import java.time.OffsetDateTime;



import io.swagger.annotations.*;
import java.util.Objects;


public class T {

  private Double amount = null;
  private String currency = null;

import javax.xml.bind.annotation.XmlEnum;
import javax.xml.bind.annotation.XmlType;

@XmlType(name="T")
@XmlEnum
public enum T {
    {values=[initial], enumVars=[{name=INITIAL, value="initial"}]}, 

    public String value() {
        return name();
    }

    public static T fromValue(String v) {
        return valueOf(v);
    }
}
  private StateEnum state = null;
...

(Ordering of imports is as-generated)

Related issues

A similar issue was reported for JaxRS-CXF in issue #3735 which was fixed a few weeks ago.

Suggest a Fix

The problem seems to be the mustache template that is used for the JaxRS-SPEC code generation. I attempted a fix but as I am wholly unfamiliar with mustache, did not get very far.

Start by reproducing the issue with the jaxrs-spec generator, the supplied YAML model, and the Maven command. Compare the jaxrs-spec Mustache template with the related JaxRS-CXF fix from issue #3735. Done means generated enum models have valid escaping and keep imports outside class declarations so the Java source compiles.