code: public static <T> T checkNotNull(final T reference, final String errorMessage) {
          return precondition(reference, Predicates.<T>notNull(),
                  IllegalArgumentException.class, errorMessage);
      }
docs: Check that a reference is not null, throwing a IllegalArgumentException if it is.
  
  @param reference    The reference to check
  @param errorMessage the message for the exception if the reference is null
  @param <T>          the type of the reference
  @throws java.lang.IllegalArgumentException if the reference is null