private boolean preferHashFieldMap(Collection<Field<T>> fields, int lastFieldNumber)
	{
		return lastFieldNumber > MIN_TAG_FOR_HASH_FIELD_MAP && lastFieldNumber >= 2 * fields.size();
	}
Generates a schema from the given class with the declared fields (inclusive) based from the given Map. The value
of a the Map's entry will be the name used for the field (which enables aliasing).
protostuff-runtime/src/main/java/io/protostuff/runtime/RuntimeSchema.java