sdk_version <= 28 implies Java 1.8

When sdk_version is equal to or less than 28, java_version is implied to
1.8 unless it is explicitly specified. It was 26 originally, and is now
updated to 28 which is the most recent API version.

Bug: 117069453
Test: EXPERIMENTAL_USE_OPENJDK9=true make apex_aidl_interface
Change-Id: I18ebe3ec51ada54103f6d203b9bfae8ec6ea5d90
diff --git a/java/java.go b/java/java.go
index 7fd5344..8b354d9 100644
--- a/java/java.go
+++ b/java/java.go
@@ -892,7 +892,7 @@
 		ret = javaVersion
 	} else if ctx.Device() && sdk <= 23 {
 		ret = "1.7"
-	} else if ctx.Device() && sdk <= 26 || !ctx.Config().TargetOpenJDK9() {
+	} else if ctx.Device() && sdk <= 28 || !ctx.Config().TargetOpenJDK9() {
 		ret = "1.8"
 	} else if ctx.Device() && sdkContext.sdkVersion() != "" && sdk == android.FutureApiLevel {
 		// TODO(ccross): once we generate stubs we should be able to use 1.9 for sdk_version: "current"