jodd-db/src/main/java/jodd/db/oom/DbEntityManager.java
public <E> DbEntityDescriptor<E> lookupType(final Class<E> type) {
		String typeName = type.getName();
		if (StringUtil.startsWithOne(typeName, primitiveEntitiesPrefixes) != -1) {
			return null;
		}
		DbEntityDescriptor<E> ded = descriptorsMap.get(type);
		if (ded == null) {
			ded = registerType(type);
		}
		return ded;
	}
public <E> DbEntityDescriptor<E> lookupType(final Class<E> type) {
		String typeName = type.getName();
		if (StringUtil.startsWithOne(typeName, primitiveEntitiesPrefixes) != -1) {
			return null;
		}
		DbEntityDescriptor<E> ded = descriptorsMap.get(type);
		if (ded == null) {
			ded = registerType(type);
		}
		return ded;
	}
Lookups {@link DbEntityDescriptor} for some type and registers the type if is new.
<p>
Returns <code>null</code> for core classes from <code>java</code> run-time packages!
Some types are <b>not</b> entities, i.e. domain objects. Instead, primitive entities
are simply mapped to one column.