Produce combined JavaDoc, add links, exclude internals
diff --git a/build.gradle b/build.gradle
index 6442429..546d3c2 100644
--- a/build.gradle
+++ b/build.gradle
@@ -32,7 +32,10 @@
         it.options.encoding = "UTF-8"
     }
 
-    javadoc.options.encoding = "UTF-8"
+    javadoc.options {
+        encoding = 'UTF-8'
+        links 'https://docs.oracle.com/javase/8/docs/api/'
+    }
 
     ext {
         libraries = [