String vocabAuthId = "vocabAuthId";
srcVarGrpBldr.setVocabularyAuthorityId( vocabAuthId );
String name = "name";
srcVarGrpBldr.addVariableBuilder( name, "descrip", "units", "vocabId", "vocabName" );
ThreddsMetadataBuilder recipientTmBldr = fac.newThreddsMetadataBuilder();
assertNotNull( recipientTmBldr);
assertTrue( recipientTmBldr.getVariableGroupBuilders().isEmpty());
ThreddsMetadataBuilderUtils.copyThreddsMetadataBuilder( srcTmBldr, recipientTmBldr );