private void setCachedEquivalence(DataTypeDB dataTypeDB, DataType dataType) {
		EquivalenceCache cache = equivalenceCache.get();
		if (cache == null) {
			throw new IllegalStateException("equivalence cache not active - unexpected condition");
		}
		long key = getEquivalenceKey(dataTypeDB, dataType);
		cache.setValue(key);
	}
Set two datatypes as equivalent within the EquivalenceCache following a
datatype resolution.

@param dataTypeDB datatype associated with this datatype manager
@param dataType   other datatype instance
Ghidra/Framework/SoftwareModeling/src/main/java/ghidra/program/database/data/DataTypeManagerDB.java