docs: public static Hashtable<String, Object> getCustomCredentials(Subject callSubject, String cacheKey) {
          if (TraceComponent.isAnyTracingEnabled() && tc.isEntryEnabled()) {
              Tr.entry(tc, "getCustomCredentials", cacheKey);
          }
          if (callSubject == null || cacheKey == null) {
              if (TraceComponent.isAnyTracingEnabled() && tc.isEntryEnabled()) {
                  Tr.exit(tc, "getCustomCredentials", " null");
              }
              return null;
          }
          GetCustomCredentials action = new GetCustomCredentials(callSubject, cacheKey);
          Hashtable<String, Object> cred = (Hashtable<String, Object>) AccessController.doPrivileged(action);
          if (TraceComponent.isAnyTracingEnabled() && tc.isEntryEnabled()) {
              Tr.exit(tc, "getCustomCredentials", objectId(cred));
          }
          return cred;
      }