FULL PRODUCT VERSION :
java version "1.6.0_11"
Java(TM) SE Runtime Environment (build 1.6.0_11-b03)
Java HotSpot(TM) Client VM (build 11.0-b16, mixed mode, sharing)

ADDITIONAL OS VERSION INFORMATION :
Windows XP Professional Version 2002 Service Pack 2

A DESCRIPTION OF THE PROBLEM :
When trying to compile java code with a simple generic method javac throws NullPointerException and produces no class files.

The code and the stacktrace are attached to the report.

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
just run javac against the given source code file

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
Get working class files

ERROR MESSAGES/STACK TRACES THAT OCCUR :
java.lang.NullPointerException
        at com.sun.tools.javac.comp.Flow.visitApply(Flow.java:1117)
        at com.sun.tools.javac.tree.JCTree$JCMethodInvocation.accept(JCTree.java:1210)
        at com.sun.tools.javac.tree.TreeScanner.scan(TreeScanner.java:35)
        at com.sun.tools.javac.tree.TreeScanner.visitExec(TreeScanner.java:157)
        at com.sun.tools.javac.tree.JCTree$JCExpressionStatement.accept(JCTree.java:1074)
        at com.sun.tools.javac.tree.TreeScanner.scan(TreeScanner.java:35)
        at com.sun.tools.javac.comp.Flow.scanStat(Flow.java:484)
        at com.sun.tools.javac.comp.Flow.scanStats(Flow.java:492)
        at com.sun.tools.javac.comp.Flow.visitBlock(Flow.java:747)
        at com.sun.tools.javac.tree.JCTree$JCBlock.accept(JCTree.java:739)
        at com.sun.tools.javac.tree.TreeScanner.scan(TreeScanner.java:35)
        at com.sun.tools.javac.comp.Flow.scanStat(Flow.java:484)
        at com.sun.tools.javac.comp.Flow.visitIf(Flow.java:1073)
        at com.sun.tools.javac.tree.JCTree$JCIf.accept(JCTree.java:1050)
        at com.sun.tools.javac.tree.TreeScanner.scan(TreeScanner.java:35)
        at com.sun.tools.javac.comp.Flow.scanStat(Flow.java:484)
        at com.sun.tools.javac.comp.Flow.scanStats(Flow.java:492)
        at com.sun.tools.javac.comp.Flow.visitBlock(Flow.java:747)
        at com.sun.tools.javac.tree.JCTree$JCBlock.accept(JCTree.java:739)
        at com.sun.tools.javac.tree.TreeScanner.scan(TreeScanner.java:35)
        at com.sun.tools.javac.comp.Flow.scanStat(Flow.java:484)
        at com.sun.tools.javac.comp.Flow.visitForeachLoop(Flow.java:864)
        at com.sun.tools.javac.tree.JCTree$JCEnhancedForLoop.accept(JCTree.java:849)
        at com.sun.tools.javac.tree.TreeScanner.scan(TreeScanner.java:35)
        at com.sun.tools.javac.comp.Flow.scanStat(Flow.java:484)
        at com.sun.tools.javac.comp.Flow.scanStats(Flow.java:492)
        at com.sun.tools.javac.comp.Flow.visitBlock(Flow.java:747)
        at com.sun.tools.javac.tree.JCTree$JCBlock.accept(JCTree.java:739)
        at com.sun.tools.javac.tree.TreeScanner.scan(TreeScanner.java:35)
        at com.sun.tools.javac.comp.Flow.scanStat(Flow.java:484)
        at com.sun.tools.javac.comp.Flow.visitMethodDef(Flow.java:693)
        at com.sun.tools.javac.tree.JCTree$JCMethodDecl.accept(JCTree.java:639)
        at com.sun.tools.javac.tree.TreeScanner.scan(TreeScanner.java:35)
        at com.sun.tools.javac.comp.Flow.visitClassDef(Flow.java:641)
        at com.sun.tools.javac.tree.JCTree$JCClassDecl.accept(JCTree.java:575)
        at com.sun.tools.javac.tree.TreeScanner.scan(TreeScanner.java:35)
        at com.sun.tools.javac.comp.Flow.analyzeTree(Flow.java:1256)
        at com.sun.tools.javac.main.JavaCompiler.flow(JavaCompiler.java:1090)
        at com.sun.tools.javac.main.JavaCompiler.flow(JavaCompiler.java:1064)
        at com.sun.tools.javac.main.JavaCompiler.compile2(JavaCompiler.java:765)
        at com.sun.tools.javac.main.JavaCompiler.compile(JavaCompiler.java:730)
        at com.sun.tools.javac.main.Main.compile(Main.java:353)
        at com.sun.tools.javac.main.Main.compile(Main.java:279)
        at com.sun.tools.javac.main.Main.compile(Main.java:270)
        at com.sun.tools.javac.Main.compile(Main.java:69)
        at com.sun.tools.javac.Main.main(Main.java:54)


REPRODUCIBILITY :
This bug can be reproduced always.

---------- BEGIN SOURCE ----------
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import java.util.TreeMap;
/*
 * JavacBug.java
 *
 */

/**
 *
 * @author Daniil Elovkov
 */
public class JavacBug {
    
    // function to transform a list of things augmented with key to a map of lists

    // THIS METHOD IS THE PROBLEM

    private <T> Map<String,List<T>> listToListMap(List<Keyed<? extends T>> list ) {
        
        Map<String,List<T>> map = new TreeMap<String,List<T>>();
        
        for (Keyed<? extends T> pair: list) {
            
            List<T> l = map.get(pair.key);
            
            if (l == null) {
                l = new ArrayList<T>( );
                l.add( pair.val );
                map.put( pair.key, l );
            } else {
                l.add( pair.val );
            }
            
        }
        
        return map;
    }
    
}

class Keyed<T extends MyClass> {
    String key;
    T val;
}

class MyClass {
}

---------- END SOURCE ----------