Make subpackage recursion explicit where these renames depend on it

[timtebeek]

Two ChangePackage rules omit recursive while depending on it to move types out of subpackages of oldPackageName.

apache-commons-math-2-3.yml — org.apache.commons.math → org.apache.commons.math3 has to carry org.apache.commons.math.stat.StatUtils along with it.

apache-httpclient-5.yml — this one is step 2 of a deliberate three-step chain:

org.apache.http.entity                          -> org.apache.hc.core5.http.io.entity      # recursive: true
org.apache.hc.core5.http.io.entity.mime         -> org.apache.hc.client5.http.entity.mime  # <-- omitted
org.apache.hc.client5.http.entity.mime.content  -> org.apache.hc.client5.http.entity.mime

Step 1 relocates org.apache.http.entity.mime.content.StringBody under core5, step 2 has to move the whole mime subtree over to client5, and step 3 flattens .content. Step 2 only reaches .content.StringBody by recursing, so without it the chain stalls at org.apache.hc.core5.http.io.entity.mime.content.StringBody — a package that doesn't exist in httpclient5.

Why now

ChangePackage.recursive is @Nullable with required = false and no documented default, and a null was read two different ways inside the same recipe: non-recursive by its preconditions, recursive by its visitor. The upshot was that a subpackage type got renamed only if the file also referenced a type sitting directly in oldPackageName — so these two rules worked in the test fixtures (which happen to mix both) and silently did nothing for a file that only touched a subpackage.

• Make a null recursive consistently mean non-recursive in ChangePackage rewrite#8382 settles null as non-recursive, which turns that latent dependency into a visible one. I found these two while validating that change downstream.

Verification

Full ./gradlew test on this branch, four ways:

	without rewrite#8382	with rewrite#8382
origin/main	0 failures	2 failures
this branch	0 failures	0 failures

• So this is correct on its own merits and safe to merge now, independently of rewrite#8382 — it makes explicit what these rules already relied on.