diff --git a/src/main/scala/sbt/internal/ProjectMatrix.scala b/src/main/scala/sbt/internal/ProjectMatrix.scala
index 539058599..9c920d69d 100644
--- a/src/main/scala/sbt/internal/ProjectMatrix.scala
+++ b/src/main/scala/sbt/internal/ProjectMatrix.scala
@@ -334,7 +334,8 @@ object ProjectMatrix {
     private def makeSources(dirSuffix: String, svDirSuffix: String): Setting[_] = {
       unmanagedSourceDirectories ++= Seq(
         scalaSource.value.getParentFile / s"scala${dirSuffix}",
-        scalaSource.value.getParentFile / s"scala$svDirSuffix"
+        scalaSource.value.getParentFile / s"scala$svDirSuffix",
+        javaSource.value.getParentFile / s"java${dirSuffix}"
       )
     }
 
diff --git a/src/sbt-test/projectMatrix/java/app/src/main/java-config1.2-jvm/com/config/MyClass.java b/src/sbt-test/projectMatrix/java/app/src/main/java-config1.2-jvm/com/config/MyClass.java
new file mode 100644
index 000000000..b714ca27b
--- /dev/null
+++ b/src/sbt-test/projectMatrix/java/app/src/main/java-config1.2-jvm/com/config/MyClass.java
@@ -0,0 +1,9 @@
+package com.config;
+
+public class MyClass {
+
+    public static String configValue() {
+        return "1.2";
+    }
+  
+}
diff --git a/src/sbt-test/projectMatrix/java/app/src/main/java-config1.3-jvm/com/config/MyClass.java b/src/sbt-test/projectMatrix/java/app/src/main/java-config1.3-jvm/com/config/MyClass.java
new file mode 100644
index 000000000..2c4800d95
--- /dev/null
+++ b/src/sbt-test/projectMatrix/java/app/src/main/java-config1.3-jvm/com/config/MyClass.java
@@ -0,0 +1,9 @@
+package com.config;
+
+public class MyClass {
+
+    public static String configValue() {
+        return "1.3";
+    }
+  
+}
diff --git a/src/sbt-test/projectMatrix/java/app/src/main/scala/com/config/Main.scala b/src/sbt-test/projectMatrix/java/app/src/main/scala/com/config/Main.scala
new file mode 100644
index 000000000..864de72cd
--- /dev/null
+++ b/src/sbt-test/projectMatrix/java/app/src/main/scala/com/config/Main.scala
@@ -0,0 +1,5 @@
+package com.config
+
+object Main extends App {
+    println(s"Version: ${MyClass.configValue()}")
+}
diff --git a/src/sbt-test/projectMatrix/java/build.sbt b/src/sbt-test/projectMatrix/java/build.sbt
new file mode 100644
index 000000000..d4532995a
--- /dev/null
+++ b/src/sbt-test/projectMatrix/java/build.sbt
@@ -0,0 +1,41 @@
+ThisBuild / organization := "com.example"
+ThisBuild / version := "0.1.0-SNAPSHOT"
+ThisBuild / publishMavenStyle := true
+
+ThisBuild / ivyPaths := {
+  val base = (ThisBuild / baseDirectory).value
+  IvyPaths(base, Some(base / "ivy-cache"))
+}
+publish / skip := true
+
+lazy val config12 = ConfigAxis("Config1_2", "-config1.2")
+lazy val config13 = ConfigAxis("Config1_3", "-config1.3")
+
+lazy val scala212 = "2.12.10"
+
+lazy val app = (projectMatrix in file("app"))
+  .settings(
+    name := "app",
+    ivyPaths := (ThisBuild / ivyPaths).value
+  )
+  .customRow(
+    scalaVersions = Seq(scala212),
+    axisValues = Seq(config12, VirtualAxis.jvm),
+    _.settings(
+      moduleName := name.value + "_config1.2",
+      libraryDependencies += "com.typesafe" % "config" % "1.2.1"
+    )
+  )
+  .customRow(
+    scalaVersions = Seq(scala212),
+    axisValues = Seq(config13, VirtualAxis.jvm),
+    _.settings(
+      moduleName := name.value + "_config1.3",
+      libraryDependencies += "com.typesafe" % "config" % "1.3.3"
+    )
+  )
+
+lazy val appConfig12_212 = app.finder(config13, VirtualAxis.jvm)(scala212)
+  .settings(
+    publishMavenStyle := true
+  )
diff --git a/src/sbt-test/projectMatrix/java/project/ConfigAxis.scala b/src/sbt-test/projectMatrix/java/project/ConfigAxis.scala
new file mode 100644
index 000000000..b1124c60e
--- /dev/null
+++ b/src/sbt-test/projectMatrix/java/project/ConfigAxis.scala
@@ -0,0 +1,5 @@
+import sbt._
+
+case class ConfigAxis(idSuffix: String, directorySuffix: String) extends VirtualAxis.WeakAxis {
+
+}
diff --git a/src/sbt-test/projectMatrix/java/project/plugins.sbt b/src/sbt-test/projectMatrix/java/project/plugins.sbt
new file mode 100644
index 000000000..4e80bbafc
--- /dev/null
+++ b/src/sbt-test/projectMatrix/java/project/plugins.sbt
@@ -0,0 +1,5 @@
+sys.props.get("plugin.version") match {
+  case Some(x) => addSbtPlugin("com.eed3si9n" % "sbt-projectmatrix" % x)
+  case _ => sys.error("""|The system property 'plugin.version' is not defined.
+                         |Specify this property using the scriptedLaunchOpts -D.""".stripMargin)
+}
diff --git a/src/sbt-test/projectMatrix/java/test b/src/sbt-test/projectMatrix/java/test
new file mode 100644
index 000000000..964c0eac1
--- /dev/null
+++ b/src/sbt-test/projectMatrix/java/test
@@ -0,0 +1,4 @@
+> publishLocal
+
+$ exists ivy-cache/local/com.example/app_config1.2_2.12/0.1.0-SNAPSHOT/poms/app_config1.2_2.12.pom
+$ exists ivy-cache/local/com.example/app_config1.3_2.12/0.1.0-SNAPSHOT/poms/app_config1.3_2.12.pom