public V put(K key, V value) {
		RedBlackEntry<K, V> node = getOrCreateEntry(key);
		V oldValue = node.getValue();
		node.setValue(value);
		return oldValue;
	}
Adds the given key,value to the map. If the map does not allow duplicate keys and a key
already exists, the old value will be replaced by the new value and the old value will be
returned. 
@param key the key to add to the set.
@return the old value associated with the key, or null if the key was not previously in the map.
Ghidra/Framework/Generic/src/main/java/ghidra/util/datastruct/RedBlackTree.java