code: public static Number multiply(BigDecimal left, Double right) {
          return NumberMath.multiply(left, right);
      }
docs: Multiply a BigDecimal and a Double.
  Note: This method was added to enforce the Groovy rule of
  BigDecimal*Double == Double. Without this method, the
  multiply(BigDecimal) method in BigDecimal would respond
  and return a BigDecimal instead. Since BigDecimal is preferred
  over Number, the Number*Number method is not chosen as in older
  versions of Groovy.
  
  @param left  a BigDecimal
  @param right a Double
  @return the multiplication of left by right
  @since 1.0