code: private String getCacheKey(String prefix, boolean flag, CmsUUID projectId, String resource) {
  
          StringBuffer b = new StringBuffer(64);
          if (prefix != null) {
              b.append(prefix);
              b.append(flag ? '+' : '-');
          }
          b.append(CmsProject.isOnlineProject(projectId) ? '+' : '-');
          return b.append(resource).toString();
      }
docs: Return a cache key build from the provided information.<p>
  
  @param prefix a prefix for the key
  @param flag a boolean flag for the key (only used if prefix is not null)
  @param projectId the project for which to generate the key
  @param resource the resource for which to generate the key
  
  @return String a cache key build from the provided information