This enhancement request is based on the use case of depending products and re-using property files.

Picture a scenario in which you have product A and product B. Both have property files (A.properties and B.properties):

[A.properties]
product.name=Product A
product.version=1.0.0
product.publish.dir=c:\publish\${product.name}\${product.version}
product.publish.file=${product.publish.dir}/${product.name}.${product.version}.zip

[B.properties]
product.name=Product B
product.version=1.0.1
product.publish.dir=c:\publish\${product.name}\${product.version}
product.publish.file=${product.publish.dir}/${product.name}.${product.version}.zip

Now let's say product B has a dependency on product A. It needs to consume files that are placed in the publish directory of product A.

So we include the property file of product A and prefix it with "A". This means we can have access to the product.publish.dir value using: ${A.product.publish.dir}

The problem is that ${A.product.publish.dir} uses the ${product.name} and ${product.version}. So in the following scenario:

<property file="B.properties" />
<property file="A.properties" prefix="A" />

The value of ${A.product.publish.dir} is actually

c:\publish\Product B\1.0.1\

It would be nice if it is possible to also prefix all properties that are used within the property file. This would make the use of the prefix attribute more compelling.

Of course there are workarounds to this situation:
A) have the prefix by design
B) copy and manipulate the property file using replace.

Therefore it should be considered as an enhancement.