code: public static <T extends FieldDescription> ElementMatcher.Junction<T> definedField(ElementMatcher<? super FieldDescription.InDefinedShape> matcher) {
          return new DefinedShapeMatcher<T, FieldDescription.InDefinedShape>(matcher);
      }
docs: Matches a field in its defined shape.
  
  @param matcher The matcher to apply to the matched field's defined shape.
  @param <T>     The matched object's type.
  @return A matcher that matches a matched field's defined shape.