The fallback event handler

The fallback pattern enables your service to continue the execution in case of a failed request to another service. Instead of aborting the computation because of a missing response, you fill in a fallback value.

Typically, Fallbacks are called when Exceptions are thrown. Exceptions can occur when the HTTP request fails, or when one of the FeignDecorators activates the CircuitBreaker.

Parameters	Description
`type`	always `fallback`
`exceptionTypes`	A collection of Exception classes that the fallback uses
`exceptionHandlerClass`	A class that handles the exception and returns an appropriate object, external
`exceptionHandler`	An object class that implements a `Function` that accepts a `Throwable` and returns an appropriate response at runtime

The following example shows the configuration code for sampleRESTApi endpoint connection:

Config.builder()
        .basePath(sampleRESTApiRule.baseUrl())
        .eventHandler(FallbackSetup.builder()
          .exceptionType(RetryableException.class)
          .exceptionHandler(t -> Collections.singletonList(SAMPLE_API))
          .build())
        .build()
        .buildAPI(sampleRESTApi.class)
        .findAll()