void putCachedEquivalence(DataTypeDB dataTypeDB, DataType dataType, boolean isEquivalent) {
		EquivalenceCache cache = equivalenceCache.get();
		if (cache == null) {
			throw new IllegalStateException("equivalence cache not active - unexpected condition");
		}
		long key = getEquivalenceKey(dataTypeDB, dataType);
		cache.putValue(key, isEquivalent);
		if (!cache.isCacheActive()) {
			clearEquivalenceCache();
		}
	}
Cache the result of {@link DataTypeDB#isEquivalent(DataType)} for select
implementations (e.g., {@link StructureDB}, {@link UnionDB}, and
{@link FunctionDefinitionDB}). The call to this method must be properly
matched up with a preceding invocation of
{@link #getCachedEquivalence(DataTypeDB, DataType)} which returned
{@code null}.

@param dataTypeDB   datatype associated with this datatype manager
@param dataType     other datatype instance
@param isEquivalent true or false result from
                    {@link DataTypeDB#isEquivalent(DataType)}.
Ghidra/Framework/SoftwareModeling/src/main/java/ghidra/program/database/data/DataTypeManagerDB.java