Caching Filter pattern

Description:
The Caching Filter design pattern aims to improve the performance and scalability of an application by caching the results of expensive operations and reusing them for identical subsequent requests. This pattern is particularly useful in scenarios where the same data is frequently requested, and the cost of recomputing the data is high.

Main Elements of the Pattern:

1. Filter: Intercepts requests and checks if a cached response is available.
2. Cache Store: A storage mechanism for saving and retrieving cached data.
3. Cache Key: A unique identifier for caching entries based on request parameters.
4. Expiration Policy: Defines how long cached data is considered valid.
5. Cache Miss Handler: Fetches data from the original source when a cache miss occurs and populates the cache.

References:

• Java Design Patterns Project Wiki
• J2EE Design Patterns

Acceptance Criteria:

1. Implement a basic Caching Filter that can intercept requests and check for cached responses.
2. Develop a simple cache store with a configurable expiration policy.
3. Ensure comprehensive unit tests are provided to validate the correct functionality of the caching mechanism.

No source file, entry point, or test location is named in the issue, so begin by reviewing the existing Java design-pattern examples in the repository and identifying where a Caching Filter belongs. Done means implementing the requested filter, cache store, expiration policy, cache-miss handling, and comprehensive unit tests.