Collectors.toMap null问题

Main.java

public class MapRecordTest {
	public static void main(String[] args) {
		
		Map<String,Object> myMap = new HashMap<>();
		myMap.put("name", null);
		System.out.println(myMap.entrySet());
		
		Map<String, Object> newMap = myMap.entrySet().stream().collect(Collectors.toMap(entry -> {
			System.out.println(entry);
			return entry.getKey().toUpperCase();
		}, entry -> {
			System.out.println(entry);
			return entry.getValue();
		}));
		System.out.println(newMap);
	}
}

/**
[name=null]
name=null
name=null
Exception in thread "main" java.lang.NullPointerException
	at java.util.HashMap.merge(Unknown Source)
	at java.util.stream.Collectors.lambda$toMap$58(Unknown Source)
	at java.util.stream.ReduceOps$3ReducingSink.accept(Unknown Source)
	at java.util.HashMap$EntrySpliterator.forEachRemaining(Unknown Source)
	at java.util.stream.AbstractPipeline.copyInto(Unknown Source)
	at java.util.stream.AbstractPipeline.wrapAndCopyInto(Unknown Source)
	at java.util.stream.ReduceOps$ReduceOp.evaluateSequential(Unknown Source)
	at java.util.stream.AbstractPipeline.evaluate(Unknown Source)
	at java.util.stream.ReferencePipeline.collect(Unknown Source)
	at com.vpu.mp.controller.admin.member.MapRecordTest.main(MapRecordTest.java:19)
  
*/

解决办法 stackflow java-8-nullpointerexception-in-collectors-tomap