docs: private String extractLikePatternPrefix() {
          assert(getExpressionType() == ExpressionType.COMPARE_LIKE);
          ConstantValueExpression cve;
          if (m_right instanceof ParameterValueExpression) {
              ParameterValueExpression pve = (ParameterValueExpression)m_right;
              cve = pve.getOriginalValue();
          }
          else {
              assert(m_right instanceof ConstantValueExpression);
              cve = (ConstantValueExpression)m_right;
          }
          String pattern = cve.getValue();
          return pattern.substring(0, pattern.length()-1);
      }