Support for incremetal platform prebuilt APIs

This change provides support for prebuilt incremental platform API (i.e.
API changes associated with a QPR, as opposed to a major dessert
releas).

This feature is provided via the existing prebuilt_apis module with the
introduction of a new attribute:

    allow_incremental_platform_api

While typical platform prebuilt APIs are presumed to be under a
directory structure that follows the pattern:

<version>/<scope>/<module>.jar
<version>/<scope>/api/<module>.txt

Where <version> is limited to a single integer signifying the API level.

For modules where allow_incremental_platform_api is set to 'true' (false
by default) the pattern is the same, however <version> is presumed to be
of the form MM.m, where MM aligns with the existing API level and m
signifies the incremental release (e.g. QPR).

Bug: b/280790094
Test: platform build check with both incremental & non-incremental API
      cd build/soong && go test ./java
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:eee6995093485497bc29cdce01c2a86765ffb4eb)
Change-Id: I67e293006ccfa210d0dcc0a294db894632f1b6cb
diff --git a/java/prebuilt_apis_test.go b/java/prebuilt_apis_test.go
index 2b84353..b6fb2c6 100644
--- a/java/prebuilt_apis_test.go
+++ b/java/prebuilt_apis_test.go
@@ -99,3 +99,26 @@
 	android.AssertStringEquals(t, "Expected latest bar = extension level 2", "prebuilts/sdk/extensions/2/public/api/bar.txt", bar_input)
 	android.AssertStringEquals(t, "Expected latest baz = api level 32", "prebuilts/sdk/32/public/api/baz.txt", baz_input)
 }
+
+func TestPrebuiltApis_WithIncrementalApi(t *testing.T) {
+	runTestWithIncrementalApi := func() (foo_input, bar_input, baz_input string) {
+		result := android.GroupFixturePreparers(
+			prepareForJavaTest,
+			FixtureWithPrebuiltIncrementalApis(map[string][]string{
+				"33.0":    {"foo"},
+				"33.1":    {"foo", "bar", "baz"},
+				"33.2":    {"foo", "bar"},
+				"current": {"foo", "bar"},
+			}),
+		).RunTest(t)
+		foo_input = result.ModuleForTests("foo.api.public.latest", "").Rule("generator").Implicits[0].String()
+		bar_input = result.ModuleForTests("bar.api.public.latest", "").Rule("generator").Implicits[0].String()
+		baz_input = result.ModuleForTests("baz.api.public.latest", "").Rule("generator").Implicits[0].String()
+		return
+	}
+	// 33.1 is the latest for baz, 33.2 is the latest for both foo & bar
+	foo_input, bar_input, baz_input := runTestWithIncrementalApi()
+	android.AssertStringEquals(t, "Expected latest foo = api level 33.2", "prebuilts/sdk/33.2/public/api/foo.txt", foo_input)
+	android.AssertStringEquals(t, "Expected latest bar = api level 33.2", "prebuilts/sdk/33.2/public/api/bar.txt", bar_input)
+	android.AssertStringEquals(t, "Expected latest baz = api level 33.1", "prebuilts/sdk/33.1/public/api/baz.txt", baz_input)
+}