SymbolDB getSymbol(DBRecord record) {
		lock.acquire();
		try {
			SymbolDB s = cache.get(record);
			if (s != null) {
				return s;
			}
			return createCachedSymbol(record);
		}
		finally {
			lock.release();
		}
	}
Called by the NamespaceManager when a namespace is removed; remove all symbols that have the
given namespace ID.

@param namespaceID ID of namespace being removed
Ghidra/Framework/SoftwareModeling/src/main/java/ghidra/program/database/symbol/SymbolManager.java