code: public void setIgnoredUserNames(Collection<String> ignoredUserNames) {
          if (ignoredUserNames == null) {
              this.ignoredUserNames = null;
          } else {
              this.ignoredUserNames = ImmutableSet.copyOf(ignoredUserNames);
          }
      }
docs: If no <code>ignoredUserNames</code> {@link Collection} is configured all user-names are
  supported otherwise exact String equality matching is done to determine ignored userNames.
  The property defaults to null (all user names)
  
  @param ignoredUserNames the ignoredUserNames to set