public class HelloWorld {
@NotEmpty
private String foo;
@NotEmpty
private String bar;
@NotEmpty
private String baz;
..
..

public HelloWorld() {
}

public UserRegistration(String foo, String bar, String baz,....)
{
 this.foo = foo;
 this.bar = bar;
 this.baz = baz;
 ..
 ..
 ..
}

public String getfoo() {
 return foo;
}

public String getbar() {
 return bar;
}

public String getbaz() {
 return baz;
}
public void setfoo(String foo) {
 this.foo = foo;
}

public void setbar(String bar) {
 this.bar = bar;
}
public void setbaz(String baz) {
 this.baz = baz;
}

}

{
      "Foo": "a",
      "bar": "b",
      "baz": "c",
       ..
       ..
 }

{
"code": 400,
"message": "Unable to process JSON"
}