code: public SystemIncludePath createSysIncludePath() {
      final Project p = getProject();
      if (p == null) {
        throw new java.lang.IllegalStateException("project must be set");
      }
      if (isReference()) {
        throw noChildrenAllowed();
      }
      final SystemIncludePath path = new SystemIncludePath(p);
      this.sysIncludePaths.addElement(path);
      return path;
    }
docs: Creates a system include path. Locations and timestamps of files located
  using the system include paths are not used in dependency analysis.
  
  
  Standard include locations should not be specified. The compiler
  adapters should recognized the settings from the appropriate environment
  variables or configuration files.