Override equals method properly on certain Wrapper objects

See build warnings like this:

```
[WARNING] .../xrpl4j/xrpl4j-core/src/main/java/org/xrpl/xrpl4j/model/transactions/Wrappers.java:[177,19] 
(immutables:incompat) Type inherits overridden 'equals' method but have some non-inherited attributes. Please override 
'equals' with abstract method to have it generate. Otherwise override with calling super implementation to use custom 
implementation
```