String xml = "<extension></extension>";

        ExtensionDescriptor ed = builder.build(toStream(xml));

        assertNotNull(ed);
        assertNotNull(ed.getExportedPackages());
        assertThat(ed.getExportedPackages(), is(empty()));
        assertNotNull(ed.getExportedArtifacts());
        assertThat(ed.getExportedArtifacts(), is(empty()));
    }

    @Test

            T[] result = super.toArray(array);
            if (size() < result.length) {
              // It works around a GWT bug where elements after last is not
              // properly null'ed.
              @Nullable Object[] unsoundlyCovariantArray = result;
              unsoundlyCovariantArray[size()] = null;
            }
            return result;
          }
        });
  }