Merge Patch Does Not Appear to Conform to RFC7396

I found that when using the example in [RFC7396](https://tools.ietf.org/html/rfc7396#section-3) that I get different results.

Given the JSON document:

```
{
"title": "Goodbye!",
"author" : {
"givenName" : "John",
"familyName" : "Doe"
},
"tags":[ "example", "sample" ],
"content": "This will be unchanged"
}
```

and the patch:

```
{
"title": "Hello!",
"phoneNumber": "+01-123-456-7890",
"author": {
"familyName": null
},
"tags": [ "example" ]
}
```

and the Json Patch code:

```
JsonValue source = Json.createValue("{\"title\":\"Goodbye!\",\"author\":{\"givenName\":\"John\",\"familyName\":\"Doe\"},\"tags\":[\"example\",\"sample\"],\"content\":\"This will be unchanged\"}");
JsonValue patch = Json.createValue("{\"title\":\"Hello!\",\"phoneNumber\":\"+01-123-456-7890\",\"author\":{\"familyName\":null},\"tags\":[\"example\"]}");

JsonMergePatch jsonMergePatch = Json.createMergePatch(patch);
JsonValue jsonValue = jsonMergePatch.apply(source);
System.out.println(jsonValue);
```

The output is:

```
{
"title": "Hello!",
"phoneNumber": "+01-123-456-7890",
"author": {
"familyName": null
},
"tags": [
"example"
]
}
```

but should be:

```
{
"title": "Hello!",
"author" : {
"givenName" : "John"
},
"tags": [ "example" ],
"content": "This will be unchanged",
"phoneNumber": "+01-123-456-7890"
}
```

1. The `author` array contents have been replaced with `"familyName": null` when the operation should have only removed the `familyName` element.
2. The `content` element has been removed. It should not have been touched.

Source code here: https://github.com/readlearncode/Java-EE-8-Only-Whats-New/blob/master/Java-API-for-JSON-Processing-1-1-JSR374/src/main/java/com/readlearncode/mergepatch/MergePatchRFC7396.java

There are the Maven coords:

```


javax.json
javax.json-api
1.1.2

org.glassfish
javax.json
1.1.2


```

Start with src/main/java/com/readlearncode/mergepatch/MergePatchRFC7396.java and compare its behavior with the RFC7396 Section 3 example shown in the issue. Verify the result using the supplied Java JSON-P example; done means familyName is removed, givenName and content remain, and the other patch changes are applied as expected.

Written by the indexing model from the issue text.