interpreter: deprecate 'jar' value of build_target(target_type)

Jar has a very low set of overlap with other target types, including
that jar sources *must* be .java, and no other target allows .java
sources. As such, the difficulty in crafting a useful `build_target`
invocation that allows both `jar` and anything else is high, and the
usefulness is dubious. Just use `jar()` directly instead.

This depends on the changes to make all of the jar() specific keyword
arguments be handled by typed_kwargs so that the deprecation messages
are correct and consistent.

1 files changed, 8 insertions, 0 deletions

diff --git a/docs/markdown/snippets/deprecate_build_target_jar.md b/docs/markdown/snippets/deprecate_build_target_jar.md
new file mode 100644
index 0000000..992903e
--- /dev/null
+++ b/docs/markdown/snippets/deprecate_build_target_jar.md
@@ -0,0 +1,8 @@
+## Deprecate 'jar' as a build_target type
+
+The point of `build_target()` is that what is produced can be conditionally
+changed. However, `jar()` has a significant number of non-overlapping arguments
+from other build_targets, including the kinds of sources it can include. Because
+of this crafting a `build_target` that can be used as a Jar and as something
+else is incredibly hard to do. As such, it has been deprecated, and using
+`jar()` directly is recomended.