8321739: Source launcher fails with "Not a directory" error

Reviewed-by: jlahoda

src/jdk.compiler/share/classes/com/sun/tools/javac/launcher/MemoryContext.java

@@ -177,7 +177,7 @@ final class MemoryContext {
         var file = descriptor.sourceRootPath().resolve(path);
 
         // Trivial case: no matching source file exists
-        if (Files.notExists(file)) return null;
+        if (!Files.exists(file)) return null;
 
         // Compile source file (unit) with similar options as the program.
         var opts = options.forSubsequentCompilations();

test/langtools/tools/javac/launcher/GetResourceTest.java

@@ -23,7 +23,7 @@
 
 /*
  * @test
- * @bug 8210009
+ * @bug 8210009 8321739
  * @summary Source Launcher classloader should support getResource and getResourceAsStream
  * @enablePreview
  * @modules jdk.compiler
@@ -41,7 +41,7 @@ import toolbox.ToolBox;
 
 /*
  * The body of this test is in ${test.src}/src/p/q/CLTest.java,
- * which is executed in single-file source-launcher mode,
+ * which is executed in source-launcher mode,
  * in order to test the classloader used to launch such programs.
  */
 public class GetResourceTest {

test/langtools/tools/javac/launcher/src/java

@@ -0,0 +1 @@
+A text file named `java` to simulate https://bugs.openjdk.org/browse/JDK-8321739