Used to filter for new or changed generic aggregate assets or normal assets.
Parameterized so that a single plugin may instantiate multiple instances
of this class to handle multiple types of assets based upon the given
String key passed in the constructor. The "interestingAsset" method
has an additional parameter, and the plugin must define this method to
handle each asset type accordingly based upon the key value.
Also may return a DynamicUnaryPredicate if so indicated by a boolean parameter
passed into the constructor