code: public final boolean execute(TemporalProposition lhs, 
              TemporalProposition rhs) {
          if (lhs == null || rhs == null) {
              return false;
          } else {
              return execute(lhs.getInterval(), rhs.getInterval());
          }
      }
docs: Returns whether two abstract parameters have a gap that satisfies
  the constraints of the gap function. If either provided parameter is
  <code>null</code>, this method returns <code>false</code>.
  
  @param lhs the first {@link AbstractParameter}.
  @param rhs the second {@link AbstractParameter}.
  @return <code>true</code> or <code>false</code>.