Make MonetaryAmount Serializable

[axiopisty]

I'm submitting this pull request to make the MonetaryAmount interface Serializable.

I realize the authors of the specification may have already discussed this and decided purposefully to not make the MonetaryAmount interface Serializable, but I have not been able to find any discussion about this. If so, then I would like to start a discussion, even if only for my own understanding, as to why it was decided that MonetaryAmount itself would not be Serializable.

[coveralls]

Coverage remained the same at 76.44% when pulling e4d5d85 on axiopisty:serializable into 1176507 on JavaMoney:master.

[keilw]

Thanks, but there have been discussions (also in downstream projects, so you may not find it in JIRA) both for JSR 354 and 363 about making API elements Serializable or not. As JSR 354 also used a few aspects and inspirations by JSR 310 (java.time) its closest equivalent https://docs.oracle.com/javase/8/docs/api/java/time/temporal/TemporalAmount.html does not extend Serializable either. Instead implementing classes like https://docs.oracle.com/javase/8/docs/api/java/time/Duration.html do. The same is followed by JSR 354 where e.g. concrete classes like Money implement Serializable in addition to MonetaryAmount but that as such doesn't. HTH, Werner

[shivamgoel]

As a best practice, concrete classes only should implement Serializable marker interface. When any of your interface does so it passes along Serializable downstream forcibly and many times unrealized.

I would recommend to go through some content regarding this area and may be tell us more about the reasoning behind making this interface extend Serializable.

Go through this as well http://efectivejava.blogspot.com/2013/07/effective-java-item-74-implement.html

[keilw]

Yes, that's what we also followed. Thanks for the pointer.

[axiopisty]

Agreed. Thank you for the dialog.

[keilw]

Thanks, it was very welcome as someone pointed out, JSR 374 (JSON-P 1.1) used it in a concrete class uder the API, Both not good to do in the API, especially if you have Java 8 and interfaces may define "default" implementations, too.