set default name to id

src/main/scala/sbt/ProjectMatrix.scala

@@ -149,6 +149,7 @@ object ProjectMatrix {
           .setPlugins(plugins)
           .configs(configurations: _*)
           .settings(
+            name := self.id,
             Keys.scalaVersion := sv,
             target := base.getAbsoluteFile / "target" / svDirSuffix.dropWhile(_ == '-'),
             crossTarget := Keys.target.value,

src/sbt-test/projectMatrix/jvm/build.sbt

@@ -1,3 +1,5 @@
+lazy val check = taskKey[Unit]("")
+
 // lazy val root = (project in file("."))
 //   .aggregate(core.projectRefs ++ app.projectRefs: _*)
 //   .settings(
@@ -5,7 +7,9 @@
 
 lazy val core = (projectMatrix in file("core"))
   .settings(
-    name := "core"
+    check := {
+      assert(moduleName.value == "core", s"moduleName is ${moduleName.value}")
+    },
   )
   .jvmPlatform(scalaVersions = Seq("2.12.8", "2.11.12"))
 

src/sbt-test/projectMatrix/jvm/test

@@ -2,3 +2,5 @@
 
 $ exists core/target/jvm-2.12/classes/a/Core.class
 $ exists core/target/jvm-2.11/classes/a/Core.class
+
+> coreJVM2_12/check