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From Brian Lenz <>
Subject AliasInterceptor parameter mapping issue
Date Fri, 28 Aug 2020 00:28:46 GMT

We are running into an issue with the AliasInterceptor after upgrading to
2.5.22 (from 2.3.35). The issue is that the fallback behavior to look in
HttpParameters for a value guarantees a value will always be set and that
Evaluated.isDefined() will subsequently always return true. The issue is
that HttpParameters.get() *always* returns a non-null value. If there isn't
an explicit value set, then it returns a Parameter.Empty. This cascades
back to AliasInterceptor, which results in the empty value *always* being
set on the stack.

As an example, let's say I have a parameter f with alias foo. If I set a
value for foo on the request, the behavior in AliasInterceptor will result
in an empty value being set for foo, thus overwriting the actual value

Is this the designed behavior? Based on the structure of the code, it
appears to be a bug since there is unnecessary logic otherwise
(specifically, the call to value.isDefined() on line 179). Further, this is
different behavior from the older versions of Struts (pre-HttpParameters).

Instead, I would think that isDefined() should be checked on the
Parameter returned
from HttpParameters so that a non-null value is only set in the Evaluated if
the parameter is actually defined.

Does anyone have any thoughts or insight into this issue? I looked in JIRA
and couldn't find anything related to it. Does anyone know of any
workarounds (aside from creating a custom AliasInterceptor to fix the



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