code: public int newField(final String owner, final String name, final String desc) {
          return newFieldItem(owner, name, desc).index;
      }
docs: Adds a field reference to the constant pool of the class being build.
  Does nothing if the constant pool already contains a similar item.
  <i>This method is intended for {@link Attribute} sub classes, and is
  normally not needed by class generators or adapters.</i>
  
  @param owner
  the internal name of the field's owner class.
  @param name
  the field's name.
  @param desc
  the field's descriptor.
  @return the index of a new or already existing field reference item.