https://github.com/neuecc/MessagePack-CSharp/blob/090c73f4d43c40ba34076f28ec57e7e0911d5de2/src/MessagePack.Generator/MessagepackCompiler.cs#L42 the document says `if input multiple csproj split with ','`, but it doesn't actually support it.
https://github.com/neuecc/MessagePack-CSharp/blob/090c73f4d43c40ba34076f28ec57e7e0911d5de2/src/MessagePack.Generator/MessagepackCompiler.cs#L42
the document says
if input multiple csproj split with ',', but it doesn't actually support it.