TranslatableComponent$Builder#addArgument

[tal5]

Additions

• TranslatableComponent$Builder#addArgument - adds a single translation argument, as opposed to the current methods which only allow setting the entire list.
• TranslatableComponentImpl#asArgument - converts a single ComponentLike into a TranslationArgument, with an optional int index for extra error info (ignored when -1, from e.g. the new addArgument ^).

Changes

• TranslatableComponentImpl$BuilderImpl.args - now defaults to null, with:
• TranslatableComponentImpl$BuilderImpl#args - acting as a getter that defaults it to a new ArrayList if unset and returns its value (similarly to other builders around the API).
• TranslatableComponentImpl$BuilderImpl#arguments - now initializes args to a new ArrayList of the correct size and adds each argument manually using the new TranslatableComponentImpl#asArgument, so that the list is mutable (unlike the one returned by asArguments) .
• TranslatableComponentImpl$BuilderImpl#build - now defaults args to Collections.emptyList() if null.

Note

TranslatableComponentImpl#asArgument's logic to include/exclude the int index param from errors may be a little messy? I don't think it's a very big problem as it's just an internal util method, but let me know if you'd prefer a different approach.
Or maybe using the string supplier variants for requireNonNull instead of computing the error strings every time.

[kezz]

why the new defensive copy here?

[tal5]

You mean the manual ArrayList? Because it needed to be a mutable list for the builder, so it couldn't use the existing asArguments (and I didn't want to change that method around because it's used in other places)