InternalCache getCache() {
    return cache;
  }
Add a {@link OngoingStubbing#thenThrow(Throwable...)} behavior to
{@param whenPoolExecute}

This method has to be {@code static} because it is called before
{@link ExecuteFunctionTestSupport} is constructed.

@param failureMode is the {@link FailureMode} that determines the kind of exception
       to {@code throw}
geode-core/src/test/java/org/apache/geode/cache/client/internal/ExecuteFunctionTestSupport.java