The "AnnotatorBuildTask" task failed unexpectedly.
System.ArgumentException: Member 'System.Void System.Diagnostics.CodeAnalysis.AllowNullAttribute::.ctor()' is declared in another module and needs to be imported
   at Mono.Cecil.MetadataBuilder.LookupToken(IMetadataTokenProvider provider)
   at Mono.Cecil.MetadataBuilder.AddCustomAttributes(ICustomAttributeProvider owner)
   at Mono.Cecil.MetadataBuilder.AddParameter(UInt16 sequence, ParameterDefinition parameter, ParamTable table)
   at Mono.Cecil.MetadataBuilder.AddParameters(MethodDefinition method)
   at Mono.Cecil.MetadataBuilder.AddMethod(MethodDefinition method)
   at Mono.Cecil.MetadataBuilder.AddMethods(TypeDefinition type)
   at Mono.Cecil.MetadataBuilder.AddType(TypeDefinition type)
   at Mono.Cecil.MetadataBuilder.AddTypes()
   at Mono.Cecil.MetadataBuilder.BuildTypes()
   at Mono.Cecil.MetadataBuilder.BuildModule()
   at Mono.Cecil.MetadataBuilder.BuildMetadata()
   at Mono.Cecil.ModuleWriter.<>c.<BuildMetadata>b__2_0(MetadataBuilder builder, MetadataReader _)
   at Mono.Cecil.ModuleDefinition.Read[TItem,TRet](TItem item, Func`3 read)
   at Mono.Cecil.ModuleWriter.BuildMetadata(ModuleDefinition module, MetadataBuilder metadata)
   at Mono.Cecil.ModuleWriter.Write(ModuleDefinition module, Disposable`1 stream, WriterParameters parameters)
   at Mono.Cecil.ModuleWriter.WriteModule(ModuleDefinition module, Disposable`1 stream, WriterParameters parameters)
   at Mono.Cecil.ModuleDefinition.Write(String fileName, WriterParameters parameters)
   at TunnelVisionLabs.ReferenceAssemblyAnnotator.Program.Main(Nullable`1 log, String referenceAssembly, String annotatedReferenceAssembly, String outputAssembly)
   at TunnelVisionLabs.ReferenceAssemblyAnnotator.AnnotatorBuildTask.Execute()
   at Microsoft.Build.BackEnd.TaskExecutionHost.Microsoft.Build.BackEnd.ITaskExecutionHost.Execute()
   at Microsoft.Build.BackEnd.TaskBuilder.ExecuteInstantiatedTask(ITaskExecutionHost taskExecutionHost, TaskLoggingContext taskLoggingContext, TaskHost taskHost, ItemBucket bucket, TaskExecutionMode howToExecuteTask)