isBlank

Returns whether the string contains only whitespace characters or is null/empty.

Example:

    assert (Strings.isBlank (null) == true);
    assert (Strings.isBlank ("   ") == true);
    assert (Strings.isBlank (" hi ") == false);

Parameters:

s	string for checking.

Returns:

true if string is null, empty, or contains only whitespace.