mobile/bind: fix comment

Change-Id: I100d1a32da7ec4f6b29f3590f23ca0a9ddbf230a
Reviewed-on: https://go-review.googlesource.com/27442
Reviewed-by: David Crawshaw <crawshaw@golang.org>
Reviewed-by: Sebastien Binet <seb.binet@gmail.com>
diff --git a/bind/genjava.go b/bind/genjava.go
index 7053abb..58e9c23 100644
--- a/bind/genjava.go
+++ b/bind/genjava.go
@@ -16,8 +16,8 @@
 // TODO(crawshaw): consider introducing Java functions for casting to and from interfaces at runtime.
 
 type JavaGen struct {
-	// javaPkg is the custom name of the Java pkg that contains the generated classes. If empty,
-	// use a package name generated from the Go package name.
+	// JavaPkg is the Java package prefix for the generated classes. The prefix is prepended to the Go
+	// package name to create the full Java package name. If JavaPkg is empty, 'go' is used as prefix.
 	JavaPkg string
 
 	*Generator