Conform toString() implementations

[QuintinWillison]

Match IntelliJ IDEA's boilerplate form, except where there's a reason to present some kind of native representation (e.g. JSON).

See this thread.

┆Issue is synchronized with this Jira Story by Unito

[vzhikserg]

I would like to suggest to use a third-party library called lombok. It helps to automatically generate a log of the boilerplate code (toString, equal, hashcode, and so on). The library is used only at compile time. It is published under the MIT license.

Example:
If we add the lombok @ToString annotation for the MessagExtras class it will generate the following output:

MessageExtras(delta=null, jsonObject={"someKey":"someValue"})