how to use a macro in ant tasks not supporting "alien" nested elements

What I am trying to do is to reduce redundancy in my build files. Unfortunately, I cannot figure out a way to circumvent ant's restrictions on nested elements.

One example is externalizing the filling of the MANIFEST, which is the same for all .jars and .ears.

I define a macro, encapsulating the manifest task with a sequential, but trying to use it in a jar task obviously results in a

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jar doesn't support the nested "createManifest" element".

Is there a sane way around these restrictions?

Thank you

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Could you instead write a macrodef to template your required jar task, including your standardized manifest section there, rather than in its own macrodef.