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:

Beginne damit, FailureDetails nachzuverfolgen, die bei Fehlern von activity-function zurückgegeben werden, und wie retryContext.getLastFailure() darauf zugreift. Vergleiche das Verhalten des Java SDK mit den anderen in der Issue erwähnten Durable-Sprachimplementierungen. Die Aufgabe ist abgeschlossen, wenn der äußerste Benutzerfehler, sein vollständig qualifizierter Typ und alle verschachtelten inneren Fehler rekursiv zur Prüfung verfügbar sind.