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8.2.7. Extending the UEL context We've seen that both the URI template values and the security constraints of @LinkResource use UEL to evaluate expressions, and we provide a basic UEL context with access only to the entity we're injecting links in, and nothing more. If you want to add more variables or functions in this context, you can by adding a @LinkELProvider annotation on the JAX-RS method, its class, or its package. This annotation's value should point to a class that implements the ELProvider interface, which wraps the default ELContext in order to add any missing functions.