title: How to define multiple friend assemblies when generating AssemblyInfo from .csproj file?
body: <p>I would like to define several friend assemblies. 
  It is easy to do so when editing the <code>AssemblyInfo</code> file manually:</p>
  
  <pre><code>[assembly:InternalsVisibleTo("Friend1a")]
  [assembly:InternalsVisibleTo("Friend1b")]
  </code></pre>
  
  <p>or</p>
  
  <pre><code>[assembly:InternalsVisibleTo("Friend2a"), 
        InternalsVisibleTo("Friend2b")]
  </code></pre>
  
  <p>However my <code>AssemblyInfo</code> file is generated by an <em>MSBuild task</em> from the <code>.csproj</code> file. In this case, I can add one <code>InternalsVisibleTo</code> attribute, but not several.</p>
  
  <pre><code>&lt;AssemblyInfo CodeLanguage="CS" OutputFile="$(AssemblyInfoFile)"  AssemblyVersion="$(Version)" InternalsVisibleTo = "Friend1a"/&gt;
  </code></pre>
  
  <p>How can I define multiple friend assemblies in my <code>.csproj</code> file?</p>