@Override
	public boolean isSigned() {
		lock.acquire();
		try {
			checkIsValid();
			initializeIfNeeded();
			return signedState == SIGNED;
		}
		finally {
			lock.release();
		}
	}
Database implementation for the enumerated data type.
Ghidra/Framework/SoftwareModeling/src/main/java/ghidra/program/database/data/EnumDB.java