Update pojo.mustache (#10353)

For setters the Jackson based property name conversion  (e. g.  from _-separated to CamelCase) is missing. So I propose this.

modules/openapi-generator/src/main/resources/JavaJaxRS/spec/pojo.mustache

@@ -47,6 +47,7 @@ import com.fasterxml.jackson.annotation.JsonValue;
     return {{name}};
   }
 
+  @JsonProperty("{{baseName}}")
   public void {{setter}}({{{datatypeWithEnum}}} {{name}}) {
     this.{{name}} = {{name}};
   }