code: public void merge(SrcTree srcTree) {
          mergeTestClassTable(srcTree.rootClassTable, rootClassTable);
          mergeTestClassTable(srcTree.subClassTable, subClassTable);
          mergeTestMethodTable(srcTree.rootMethodTable, rootMethodTable);
          mergeTestMethodTable(srcTree.subMethodTable, subMethodTable);
          mergeTestFieldTable(srcTree.fieldTable, fieldTable);
      }
docs: (since merging can break correct reference)