I have a hashmap of the following structure:-

```
mymap = {a:{b:{c:{d:{e}}}}

```

How do I check the existance of key "d" in hashmap mymap in the simplest way?
Is there any Java8 features that might come in handy here?

```
mymap.get( "a" )).get( "b" )..; 

```

**is not going to work because I don't know the level in which d is nested.** 
How do I check if d is present in the map, and get its value without this trailing call? Thanks in advance.