Constructor with required attributes is not generated correctly when there is inheritance.

[jjjasper]

This issue occurs when the first schema is defined in a "common" spec, or is an existing class, and a second spec refers to the previously generated class using `schemaMapping'

When a class defines a required property

    public AbstractSuperClass(String currency) {
      super();
          this.currency = currency;
    }

then the subclass

    /**
    * Constructor with only required parameters
    */
    public ConcreteSubClass(String currency) {
      super();
    }