code: public FaunusPipeline has(final String key, final Object... values) {
          return (values.length == 0) ? this.has(key, Compare.NOT_EQUAL, new Object[]{null}) : this.has(key, Compare.EQUAL, values);
      }
docs: Emit the current element it has a property value equal to the provided values.
  
  @param key    the property key of the element
  @param values the values to compare against where only one needs to succeed (or'd)
  @return the extended FaunusPipeline