Unless otherwise specified in a particular implementation, the
collections returned by methods in this package should be expected
to be unmodifiable by the caller and unsafe for concurrent access.
Unless otherwise specified, methods in this package will throw
a NullPointerException if given a null argument.
Unless otherwise specified in a particular implementation, the collections returned by methods in this package should be expected to be unmodifiable by the caller and unsafe for concurrent access.
Unless otherwise specified, methods in this package will throw a NullPointerException if given a null argument.