code: public String getResolutionReportString() {
          ResolutionReport report = _reportRef.get();
          StringBuilder reportMessage = null;
          if (report != null) {
              Map<Resource, List<ResolutionReport.Entry>> unresolved;
              reportMessage = new StringBuilder().append("Resolver report:\n");
              unresolved = report.getEntries();
              if (!unresolved.isEmpty()) {
                  for (Resource resource : unresolved.keySet()) {
                      reportMessage.append(report.getResolutionReportMessage(resource));
                  }
              }
              if (report.getResolutionException() != null) {
                  reportMessage.append("\nResolution exception:\n" + report.getResolutionException());
              }
          }
          return reportMessage == null ? "No resolution report generated." : reportMessage.toString();
      }
docs: Convenience method to get a string to use for debug tracing.
  
  @return A string describing any unresolved resources or resolution exception.