adding an option so java models can implement Serializable

modules/swagger-codegen/src/main/java/io/swagger/codegen/languages/JavaClientCodegen.java

@@ -35,6 +35,8 @@ public class JavaClientCodegen extends DefaultCodegen implements CodegenConfig {
     protected String artifactVersion = "1.0.0";
     protected String sourceFolder = "src/main/java";
     protected String localVariablePrefix = "";
+    protected Boolean serializableModel = false;
+    
     public JavaClientCodegen() {
         super();
         outputFolder = "generated-code/java";
@@ -75,6 +77,7 @@ public class JavaClientCodegen extends DefaultCodegen implements CodegenConfig {
         cliOptions.add(new CliOption("artifactVersion", "artifact version in generated pom.xml"));
         cliOptions.add(new CliOption("sourceFolder", "source folder for generated code"));
         cliOptions.add(new CliOption("localVariablePrefix", "prefix for generated code members and local variables"));
+        cliOptions.add(new CliOption("serializableModel", "boolean - toggle \"implements Serializable\" for generated models"));
     }
 
     public CodegenType getTag() {
@@ -129,6 +132,12 @@ public class JavaClientCodegen extends DefaultCodegen implements CodegenConfig {
         if (additionalProperties.containsKey("localVariablePrefix")) {
             this.setLocalVariablePrefix((String) additionalProperties.get("localVariablePrefix"));
         }
+        
+        if (additionalProperties.containsKey("serializableModel")) {
+            this.setSerializableModel(Boolean.valueOf((String)additionalProperties.get("serializableModel")));
+        } else {
+            additionalProperties.put("serializableModel", serializableModel);
+        }
 
         this.sanitizeConfig();
 
@@ -364,6 +373,14 @@ public class JavaClientCodegen extends DefaultCodegen implements CodegenConfig {
         this.localVariablePrefix = localVariablePrefix;
     }
 
+    public Boolean getSerializableModel() {
+        return serializableModel;
+    }
+
+    public void setSerializableModel(Boolean serializableModel) {
+        this.serializableModel = serializableModel;
+    }
+    
     private String sanitizePackageName(String packageName) {
         packageName = packageName.trim();
         packageName = packageName.replaceAll("[^a-zA-Z0-9_\\.]", "_");

modules/swagger-codegen/src/main/resources/Java/model.mustache

@@ -3,6 +3,9 @@ package {{package}};
 {{#imports}}import {{import}};
 {{/imports}}
 
+{{#serializableModel}}
+import java.io.Serializable;{{/serializableModel}}
+
 import io.swagger.annotations.*;
 import com.fasterxml.jackson.annotation.JsonProperty;
 {{#models}}
@@ -13,7 +16,7 @@ import com.fasterxml.jackson.annotation.JsonProperty;
  **/{{/description}}
 @ApiModel(description = "{{{description}}}")
 {{>generatedAnnotation}}
-public class {{classname}} {{#parent}}extends {{{parent}}}{{/parent}} {
+public class {{classname}} {{#parent}}extends {{{parent}}}{{/parent}} {{#serializableModel}}implements Serializable{{/serializableModel}} {
   {{#vars}}{{#isEnum}}
   public enum {{datatypeWithEnum}} {
     {{#allowableValues}}{{#values}} {{.}}, {{/values}}{{/allowableValues}}