* message: The size of {item} must be between {min} and {max}.
     * </pre>
     * @param property The property name for the message. (NotNull)
     * @param min The parameter min for message. (NotNull)
     * @param max The parameter max for message. (NotNull)
     * @return this. (NotNull)
     */
    public FessMessages addConstraintsSizeMessage(String property, String min, String max) {
        assertPropertyNotNull(property);

     * @param propertyKey The key of the property. (NotNull)
     * @return The value of found property. (NotNull: if not found, exception)
     * @throws ConfigPropertyNotFoundException When the property is not found.
     */
    String get(String propertyKey);

    /**
     * Is the property true?
     * @param propertyKey The key of the property which is boolean type. (NotNull)

     * @param level The parameter value of level. (NotNull)
     */
    public void setLevel(String level) {
        registerVariable("level", level);
    }

    /**
     * Set the value of hostname, used in parameter comment. <br>
     * Even if empty string, treated as empty plainly. So "IF pmb != null" is false if empty.
     * @param hostname The parameter value of hostname. (NotNull)
     */

        MultiValidationBean bean = new MultiValidationBean();
        bean.setRequiredCron(null); // Violates NotNull

        Set<ConstraintViolation<MultiValidationBean>> violations = validator.validate(bean);
        assertEquals(1, violations.size()); // Only NotNull violation

        bean.setRequiredCron("invalid"); // Now violates CronExpression
        violations = validator.validate(bean);

        return "Predicates.isNull()";
      }
    },
    /**
     * @see Predicates#notNull()
     */
    NOT_NULL {
      @Override
      public boolean apply(@Nullable Object o) {
        return o != null;
      }

      @Override
      public String toString() {
        return "Predicates.notNull()";
      }
    };

    @SuppressWarnings("unchecked") // safe contravariant cast

        return "Predicates.isNull()";
      }
    },
    /**
     * @see Predicates#notNull()
     */
    NOT_NULL {
      @Override
      public boolean apply(@Nullable Object o) {
        return o != null;
      }

      @Override
      public String toString() {
        return "Predicates.notNull()";
      }
    };

    @SuppressWarnings("unchecked") // safe contravariant cast

  }

  public void testNotNull_apply() {
    Predicate<@Nullable Integer> notNull = Predicates.notNull();
    assertFalse(notNull.apply(null));
    assertTrue(notNull.apply(1));
  }

  public void testNotNull_equality() {
    new EqualsTester()
        .addEqualityGroup(Predicates.notNull(), Predicates.notNull())
        .addEqualityGroup(Predicates.isNull())
        .testEquals();
  }

   * throws a {@link NullPointerException}.
   *
   * <p>To find the first non-null element in an iterable, use {@code Iterables.find(iterable,
   * Predicates.notNull())}. For varargs, use {@code Iterables.find(Arrays.asList(a, b, c, ...),
   * Predicates.notNull())}, static importing as necessary.
   *
   * <p><b>Note:</b> if {@code first} is represented as an {@link Optional}, this can be

          <item index="5" class="java.lang.String" itemvalue="io.reactivex.annotations.NonNull" />
          <item index="6" class="java.lang.String" itemvalue="io.reactivex.rxjava3.annotations.NonNull" />
          <item index="7" class="java.lang.String" itemvalue="jakarta.annotation.Nonnull" />
          <item index="8" class="java.lang.String" itemvalue="javax.annotation.Nonnull" />

   * throws a {@link NullPointerException}.
   *
   * <p>To find the first non-null element in an iterable, use {@code Iterables.find(iterable,
   * Predicates.notNull())}. For varargs, use {@code Iterables.find(Arrays.asList(a, b, c, ...),
   * Predicates.notNull())}, static importing as necessary.
   *
   * <p><b>Note:</b> if {@code first} is represented as an {@link Optional}, this can be