Use Java 1.8 when generating build files

Bug: 320294595
Test: m
Change-Id: I5d4405001e02f2baa56650203be23caceb1094c0
diff --git a/cmd/pom2bp/pom2bp.go b/cmd/pom2bp/pom2bp.go
index 3fb4454..6d1caf9 100644
--- a/cmd/pom2bp/pom2bp.go
+++ b/cmd/pom2bp/pom2bp.go
@@ -651,7 +651,7 @@
         {{- end}}
     ],
     {{- end}}
-    java_version: "1.7",
+    java_version: "1.8",
 }
 `))