allow configuring jackson, remove jackson import if disabled

Author: rignicat

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

@@ -119,6 +119,7 @@ public void processOpts() {
         convertPropertyToStringAndWriteBack(CodegenConstants.IMPL_FOLDER, this::setImplFolder);
         convertPropertyToBooleanAndWriteBack(USE_BEANVALIDATION, this::setUseBeanValidation);
         convertPropertyToBooleanAndWriteBack(USE_TAGS, this::setUseTags);
+        convertPropertyToBooleanAndWriteBack(JACKSON, this::setJackson);
     }
 
     @Override

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

@@ -276,6 +276,7 @@ public CodegenModel fromModel(String name, Schema model) {
         if (!jackson) {
             codegenModel.imports.remove("JsonValue");
             codegenModel.imports.remove("JsonProperty");
+            codegenModel.imports.remove("JsonTypeName");
         }
         return codegenModel;
     }