Implementers of this interface are strongly advised to not have the
throw any exception. It is supposed that the close operation cannot fail. Only in case of an
unexpected error the implementers can throw a runtime exception.
AutoCloseable.close(), cases where the close may fail require careful attention. It is strongly advised to relinquish the underlying resources and to internally mark the
Closeableas closed, prior to throwing an exception.
trueif the current object is closed.