protected static <T> T firstOf(Iterable<T> of) {
		Iterator<T> it = of.iterator();
		return it.hasNext() ? it.next() : null;
	}
Iterate over the entries as ordered by the index

<p>
Each entry is a key-value value where the "key" is the value of the indexed field, and the
"value" is the object.

@return the iterator
Ghidra/Debug/ProposedUtils/src/main/java/ghidra/util/database/DBCachedObjectIndex.java