Method checkOpened

app/src/main/java/com/sun/mail/imap/IMAPFolder.java:452–464

()

     * ASSERT: Must be called with this folder's synchronization lock held.
     */
    protected void checkOpened() throws FolderClosedException {
	assert Thread.holdsLock(this);
	if (!opened) {
	    if (reallyClosed)
		throw new IllegalStateException(
		    "This operation is not allowed on a closed folder"
	    	);
	    else // Folder was closed "implicitly"
		throw new FolderClosedException(this, 
		    "Lost folder connection to server"
		);
	}
    }

    /*
     * Check that the given message number is within the range