NULL HttpEntity in headerFunction in HTTP inbound gateway

[andreiamariei]

When trying to upgrade from version 5.1.8 to 5.2.1, our HTTP inbound gateway started throwing NPEs when evaluating header functions. Our code is quite basic:

IntegrationFlows.from(
                        inboundGateway( gatewayPath )
                                .headerFunction(SOME_HEADER, ent -> getSomeHeaderValue(ent ) )  // ent is null

Seems to be related to the call FunctionExpression.getValue(...) which ignores EvaluationContext.getRootObject()

Do you need more info on this?

[artembilan]

Confirmed.
Looks like FunctionExpression has to be fixed:

	public Object getValue(EvaluationContext context, Object rootObject) throws EvaluationException {
		return getValue(rootObject);
	}

The rootObject might be null, so we need to consult with the context for that one instead.

Would you mind to provide a fix?

Thanks

[artembilan]

The regression has been done here: 8f86ef9#diff-9f816d4b97a4332fc0368b15f4fdbc8aR277.

Where it calls an Expression.getValue(EvaluationContext context, Object rootObject, @Nullable Class<T> desiredResultType) with null for rootObject.
This is not what we should call according SpEL contract. So, the fix must be done in the ExpressionEvalMap.

Although FunctionExpression may be effected with some refactoring as well.

Looks like a bit involved - will fix soon...