Compile and run test case below ( javac/api/Diagnostic/DiagnosticTest08/DiagnosticTest08.java).
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import java.util.Arrays;
import javax.tools.*;
// This test for the message kind note.

public class DiagnosticTest08 {
    static volatile int passed = 0, failed = 0;
    static void pass() { passed++; }
    static void fail() { failed++; Thread.dumpStack(); }
    static void fail(String msg) { System.out.println(msg); fail(); }
    static void unexpected(Throwable t) { failed++; t.printStackTrace(); }
    static void check(boolean cond) { if (cond) pass(); else fail(); }
    static void equal(Object x, Object y) {
        if (x == null ? y == null : x.equals(y)) pass();
        else {System.out.println(x + " not equal to " + y); fail(); }}
    public static void main(String... arg) throws Throwable {
                        String javafilename = "DiagnosticTest08.java";
                        if(arg.length > 0) javafilename = arg[0];
        JavaCompiler javac = ToolProvider.getSystemJavaCompiler();
        DiagnosticCollector dc = new DiagnosticCollector();
        StandardJavaFileManager sjfm = javac.getStandardFileManager(null,null,null);
        Iterable<? extends JavaFileObject> ite = sjfm.getJavaFileObjects(javafilename);
        JavaCompiler.CompilationTask task =
                javac.getTask(null,sjfm,dc,null,null,ite);
        task.call();
        int i=0;
        for(Object message : dc.getDiagnostics()) {
            Diagnostic d = (Diagnostic)message;
            equal(d.getSource().toString(),javafilename); //<=NullPointerException on call to toString()
            equal(d.getKind().toString(),"NOTE");
            if(i == 0)
            equal(d.getCode().toString(),"compiler.note.unchecked.filename");
            else equal(d.getCode().toString(),"compiler.note.unchecked.recompile");
            equal(d.getColumnNumber(),-1l);
            equal(d.getStartPosition(),-1l);
            equal(d.getEndPosition(),-1l);
            equal(d.getLineNumber(),-1l);
            equal(d.getPosition(),-1l);
            i++;
        }
        System.out.printf("%nPassed = %d, failed = %d%n%n", passed, failed);
            if (failed > 0) throw new Exception("Some tests failed");
    }
}