code: public String getPackageId() {
  		StringBuilder sb = new StringBuilder();
  		if (group != null) sb.append(group);
  		sb.append(":");
  		if (name != null) sb.append(name);
  		sb.append(":");
  		if (version != null) sb.append(version);
  		sb.append(":");
  		return sb.toString();
  	}
docs: Get a reasonable unique ID for the package.
  
  @return The package ID