code: public PropertyConstraint ifTrue(PropertyConstraint ifConstraint, PropertyConstraint[] thenConstraints,
  			PropertyConstraint[] elseConstraints) {
  		return new ConditionalPropertyConstraint(ifConstraint,
  				new CompoundPropertyConstraint(new And(thenConstraints)), new CompoundPropertyConstraint(new And(
  						elseConstraints)));
  	}
docs: Returns a ConditionalPropertyConstraint: one property will trigger the
  validation of another.
  
  @see ConditionalPropertyConstraint