FailureDetails.IsCausedBy throws

When an activity function throws an exception, and it is caught by a custom retry handler in an orchestrator, the retryContext allows accessing the FailureDetails for analysis of the failure. However, attempting to use the FailureDetails.isCausedBy() method will never succeed, as it internally is implemented using Class.forName() which requires the fully-qualified exception class name but FailureDetails does not have this information serialized, just the simple exception class name.

Repro:

    @FunctionName("CustomRetryActivityFunction")
    public String customRetryActivityFunction(
            @DurableOrchestrationTrigger(name = "ctx") TaskOrchestrationContext ctx) {
        TaskOptions options = new TaskOptions(retryContext -> {
            FailureDetails lastFailure = retryContext.getLastFailure();
            if (lastFailure != null
                    && lastFailure.getErrorType().equals("OverflowException")
                    // This line should work, but doesn't
                    // && lastFailure.isCausedBy(InvalidOperationException.class)
                    && retryContext.getLastAttemptNumber() < 3) {
                return true;
            }
            return false;
        });
        return ctx.callActivity("RaiseComplexException", ctx.getInstanceId(), options, String.class).await();
    }
``

从 FailureDetails.isCausedBy() 开始，追踪 failure 的错误类型在通过 retryContext 访问时如何被序列化和重建。使用提供的自定义重试处理器和异常场景来复现该 failure。完成的标准是 isCausedBy() 能够成功评估 cause class，并且为复现的案例提供覆盖率。