Simple provisional persistence implementation for item filter. It has a few issues of various
importance:
- Like the current filter variants, it is non-canonical: MEMBER_OF can be rewritten as an OR of
EQUALs, and similarly with the TYPE variants. INTERVAL can be expressed as an AND of LESS and
MORE. (Apart from the API omission that closedness cannot by expressed in the latter two.)
- The current XML structure isn't as simple as it could be, and not easily verifiable by a
simple schema.
- Delegation responsibilities to sub-filters and content types for persisting and parsing
aren't very clear.
- Behavior with unpersistable sub-filters and content types is somewhat unspecified.
- Content types for values use the internal legacy ad-hoc identifiers. It would be better to
use well specified (standardized) expressions where possible (units/kind-of-quantities, Java
classes, as in "JMX 2.0").