public Entry<K, T> lowerEntry(K key) {
		return firstOf(head(key, false).descending().entries());
	}
Get the entry before the given key

@param key the key
@see #descending()
@see #sub(Object, boolean, Object, boolean)
@return the entry of the previous key, or null
Ghidra/Debug/ProposedUtils/src/main/java/ghidra/util/database/DBCachedObjectIndex.java