code: @Override
      public final boolean accept(final T candidate) throws IllegalStateException {
  
          // Check sanity
          if (log == null) {
              throw new IllegalStateException("Filter [" + getClass().getSimpleName() + "] not initialized before use.");
          }
  
          // Should we process null values?
          if (candidate == null) {
  
              boolean toReturn = false;
              if (processNullValues) {
                  toReturn = onNullCandidate();
              } else {
                  if (log.isDebugEnabled()) {
                      log.debug("Received null candidate, and Filter [" + getClass().getSimpleName()
                              + "] is configured not to match nulls.");
                  }
              }
  
              // All done.
              return toReturn;
          }
  
          // Delegate processing.
          return onCandidate(candidate);
      }
docs: {@inheritDoc}