PROPOSAL: The following directory structures should be supported by NMaven command-line builds as well as the Visual Studio Addin.
1. Typical Maven single-module structure, single pom with separate source trees for code and tests. (Visual Studio seems to see the two source trees as separate "projects" each with a .csproj or .vbproj file.)
2. Typical Maven multi-module structure, parent pom with modules, subdirectories for modules, each module containing source and tests as in 1.
3. Visual Studio flat structure with .sln, .csproj and source code all in the same directory.
4. Visual Studio multi-module project with a parent pom containing modules, then a subdirectory for each module, which equates to a VS "project". The .sln file sits beside the parent pom, and each subdirectory contains a .csproj, pom.xml and source code. Source code is not typically put in a subdirectory under the module, but it might be.