RCP Application PDE build generated feature.xml unpack=false

Question

I try to building my RCP application with the following help: http://help.eclipse.org/luna/index.jsp?topic=%2Forg.eclipse.pde.doc.user%2Ftasks%2Fpde_product_build.htm

I only have one plugin and no feature. Because of that I try to generate one in my customTargets.xml.

During the target customAssembly I recieve the error:

C:\xyz\build\package.xyz.rcpSampleFeature.xml:193: C:xyz\build\tmp\rcpSample\plugins\com.ibm.icu_52.1.1.v201501240615 d oes not exist.

I did some google research and found out, that my generated feature.xml sets the attribute unpack=true for all my plugins. Because of that the pde builder expects a directory, but it's actually a .jar archieve. Changing the attribute to unpack=false should solve the problem.

My question is, how can I generate my feature with unpack=false for all the plugins?

I tried:

<eclipse.generateFeature
        featureId="xyz.rcpSampleFeature"
        buildDirectory="${buildDirectory}"
        baseLocation="${baseLocation}"
        productFile="${product}"
        verify="false"
        pluginPath="${pluginPath}"
        configInfo="${configs}"
        pluginList="xyz.rcpSample;unpack=false"
        featureList="${featureList}"
        includeLaunchers="false"
    />

But this only adds the plugin a second time with unpack=false:

feature id="xyz.rcpSampleFeature" version="1.0.0">
    <plugin id="xyz.rcpSample" version="0.0.0" unpack="false"/>
    <plugin id="com.ibm.icu" version="0.0.0" unpack="true"/>
    <plugin id="xyz.rcpSample" version="0.0.0" unpack="true"/>
    <plugin id="javax.annotation" version="0.0.0" unpack="true"/>

...

Does anyone know a solution? Thanks in advance.