code: public void add(Collection<ConfigurationMetadataSource> sources) {
  		for (ConfigurationMetadataSource source : sources) {
  			String groupId = source.getGroupId();
  			ConfigurationMetadataGroup group = this.allGroups.get(groupId);
  			if (group == null) {
  				group = new ConfigurationMetadataGroup(groupId);
  				this.allGroups.put(groupId, group);
  			}
  			String sourceType = source.getType();
  			if (sourceType != null) {
  				putIfAbsent(group.getSources(), sourceType, source);
  			}
  		}
  	}
docs: Register the specified {@link ConfigurationMetadataSource sources}.
  @param sources the sources to add