Only the innermost exception is returned when activity functions throw

When an activity function throws an exception, we return a FailureDetails but it only represents the innermost exception. Request changing this behavior to match the other durable language implementations returning the outermost user error and all inner errors recursively.

Repro code:

    @FunctionName("CustomRetryActivityFunction")
    public String customRetryActivityFunction(
            @DurableOrchestrationTrigger(name = "ctx") TaskOrchestrationContext ctx) {
        TaskOptions options = new TaskOptions(retryContext -> {
            FailureDetails lastFailure = retryContext.getLastFailure();
            if (lastFailure != null
                    // BUG: Only the innermost failure is available in the Java SDK
                    // BUG: isCausedBy() relies on Class.forName() but we do not provide the fully qualified class name
                    //      in the FailureDetails 
                    && lastFailure.getErrorType().equals("OverflowException")
                    // && lastFailure.isCausedBy(InvalidOperationException.class)
                    // BUG: We do not implement inner failures in the Java SDK yet
                    // && lastFailure.getInnerFailure() != null
                    // && lastFailure.getInnerFailure().isCausedBy("java.lang.OverflowException")
                    && retryContext.getLastAttemptNumber() < 3) {
                return true;
            }
            return false;
        });
        return ctx.callActivity("RaiseComplexException", ctx.getInstanceId(), options, String.class).await();
    }

    @FunctionName("RaiseComplexException")
    public String raiseComplexException(
            @DurableActivityTrigger(name = "instanceId") String instanceId,
            final ExecutionContext context) throws InvalidOperationException {
        AtomicInteger count = globalRetryCount.computeIfAbsent(instanceId, k -> new AtomicInteger(0));
        int current = count.incrementAndGet();
        if (current == 1) {
            OverflowException inner = new OverflowException("Inner exception message");
            InvalidOperationException ex = new InvalidOperationException(
                "This activity failed\r\nMore information about the failure", inner);
            throw ex;
        } else {
            return "Success";
        }
    }

Result:

Inizia tracciando i FailureDetails restituiti per gli errori di activity-function e il modo in cui retryContext.getLastFailure() li espone. Confronta il comportamento del Java SDK con le altre implementazioni Durable nei linguaggi menzionate nell’issue. Il lavoro è completo quando l’errore utente più esterno, il suo tipo completamente qualificato e tutti gli errori interni annidati sono disponibili per un’ispezione ricorsiva.