public static Long checkNotZero(Long reference, String errorMsg) {
		if (reference == null || reference == 0L) {
			throw new IllegalArgumentException(errorMsg);
		}
		return reference;
	}
Ensures that an object reference passed as a parameter to the calling method is not 0.

@param reference an object reference
@param errorMsg  error messgae.
@return the non-null reference that was validated
ngrinder-core/src/main/java/org/ngrinder/common/util/Preconditions.java