Update java-extension.md

taowen · web-flow · commit efa58d85eefb · 2016-12-19T22:48:54.000+08:00
diff --git a/java-extension.md b/java-extension.md
@@ -3,6 +3,9 @@ layout: default
 title: How to extend
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+* TOC
+{:toc}
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 # Bind-api extension
 
 Bind-api is the most complex api. Iterating the json input, while binding to a object graph has infinite ways to customize. 
