Map<String, ProjectRepository> parentRepositoriesMap = createRepositoriesMap( parentRepositories );
for ( Map.Entry<String, ProjectRepository> entry : mainRepositoriesMap.entrySet() )
{
String key = entry.getKey();
ProjectRepository mainProjectRepository = entry.getValue();
ProjectRepository parentProjectRepository = parentRepositoriesMap.get( key );
if ( parentProjectRepository == null )
{
merged.add( mainProjectRepository );
}