diff --git a/project/Docs.scala b/project/Docs.scala
index f8d433e..88a854a 100644
--- a/project/Docs.scala
+++ b/project/Docs.scala
@@ -26,7 +26,7 @@
 object Docs extends sbt.Build {
   lazy val javadocSettings = Seq(
     addCompilerPlugin(
-      "com.typesafe.genjavadoc" %% "genjavadoc-plugin" % "0.9" cross CrossVersion.full),
+      "com.typesafe.genjavadoc" %% "genjavadoc-plugin" % "0.11" cross CrossVersion.full),
     scalacOptions += s"-P:genjavadoc:out=${target.value}/java"
   )
 
diff --git a/streaming/src/main/scala/org/apache/gearpump/streaming/dsl/api/functions/FilterFunction.scala b/streaming/src/main/scala/org/apache/gearpump/streaming/dsl/api/functions/FilterFunction.scala
index 8d3ffb3..49280dc 100644
--- a/streaming/src/main/scala/org/apache/gearpump/streaming/dsl/api/functions/FilterFunction.scala
+++ b/streaming/src/main/scala/org/apache/gearpump/streaming/dsl/api/functions/FilterFunction.scala
@@ -31,7 +31,7 @@
 /**
  * Returns true to keep the input and false otherwise.
  *
- * @param T Input value type
+ * @tparam T Input value type
  */
 abstract class FilterFunction[T] extends SerializableFunction {
 
diff --git a/streaming/src/main/scala/org/apache/gearpump/streaming/dsl/api/functions/FoldFunction.scala b/streaming/src/main/scala/org/apache/gearpump/streaming/dsl/api/functions/FoldFunction.scala
index 1525d6e..9647a6e 100644
--- a/streaming/src/main/scala/org/apache/gearpump/streaming/dsl/api/functions/FoldFunction.scala
+++ b/streaming/src/main/scala/org/apache/gearpump/streaming/dsl/api/functions/FoldFunction.scala
@@ -21,8 +21,8 @@
 /**
  * Combines input into an accumulator.
  *
- * @param A type of accumulator
- * @param T Type of input
+ * @tparam A type of accumulator
+ * @tparam T Type of input
  */
 abstract class FoldFunction[T, A] extends SerializableFunction {
 
diff --git a/streaming/src/main/scala/org/apache/gearpump/streaming/dsl/api/functions/MapFunction.scala b/streaming/src/main/scala/org/apache/gearpump/streaming/dsl/api/functions/MapFunction.scala
index 7880c2f..62140af 100644
--- a/streaming/src/main/scala/org/apache/gearpump/streaming/dsl/api/functions/MapFunction.scala
+++ b/streaming/src/main/scala/org/apache/gearpump/streaming/dsl/api/functions/MapFunction.scala
@@ -31,8 +31,8 @@
 /**
  * Transforms an input into an output of possibly different types.
  *
- * @param T Input value type
- * @param R Output value type
+ * @tparam T Input value type
+ * @tparam R Output value type
  */
 abstract class MapFunction[T, R] extends SerializableFunction {
 
diff --git a/streaming/src/main/scala/org/apache/gearpump/streaming/dsl/api/functions/ReduceFunction.scala b/streaming/src/main/scala/org/apache/gearpump/streaming/dsl/api/functions/ReduceFunction.scala
index 25f157b..6b84901 100644
--- a/streaming/src/main/scala/org/apache/gearpump/streaming/dsl/api/functions/ReduceFunction.scala
+++ b/streaming/src/main/scala/org/apache/gearpump/streaming/dsl/api/functions/ReduceFunction.scala
@@ -31,7 +31,7 @@
 /**
  * Combines two inputs into one output of the same type.
  *
- * @param T Type of both inputs and output
+ * @tparam T Type of both inputs and output
  */
 abstract class ReduceFunction[T] extends FoldFunction[T, Option[T]] {
 
diff --git a/streaming/src/main/scala/org/apache/gearpump/streaming/dsl/javaapi/functions/FlatMapFunction.scala b/streaming/src/main/scala/org/apache/gearpump/streaming/dsl/javaapi/functions/FlatMapFunction.scala
index adad878..35e8783 100644
--- a/streaming/src/main/scala/org/apache/gearpump/streaming/dsl/javaapi/functions/FlatMapFunction.scala
+++ b/streaming/src/main/scala/org/apache/gearpump/streaming/dsl/javaapi/functions/FlatMapFunction.scala
@@ -23,8 +23,8 @@
  * Transforms one input into zero or more outputs of possibly different types.
  * This Java version of FlatMapFunction returns a java.util.Iterator.
  *
- * @param T Input value type
- * @param R Output value type
+ * @tparam T Input value type
+ * @tparam R Output value type
  */
 abstract class FlatMapFunction[T, R] extends SerializableFunction {
 
diff --git a/streaming/src/main/scala/org/apache/gearpump/streaming/dsl/javaapi/functions/GroupByFunction.scala b/streaming/src/main/scala/org/apache/gearpump/streaming/dsl/javaapi/functions/GroupByFunction.scala
index 5a86a86..22c40d5 100644
--- a/streaming/src/main/scala/org/apache/gearpump/streaming/dsl/javaapi/functions/GroupByFunction.scala
+++ b/streaming/src/main/scala/org/apache/gearpump/streaming/dsl/javaapi/functions/GroupByFunction.scala
@@ -22,8 +22,8 @@
 /**
  * Assigns the input value into a group.
  *
- * @param T Input value type
- * @param GROUP Group value type
+ * @tparam T Input value type
+ * @tparam GROUP Group value type
  */
 abstract class GroupByFunction[T, GROUP] extends MapFunction[T, GROUP] {
 
diff --git a/streaming/src/main/scala/org/apache/gearpump/streaming/dsl/scalaapi/functions/FlatMapFunction.scala b/streaming/src/main/scala/org/apache/gearpump/streaming/dsl/scalaapi/functions/FlatMapFunction.scala
index 2d26df6..881ddc3 100644
--- a/streaming/src/main/scala/org/apache/gearpump/streaming/dsl/scalaapi/functions/FlatMapFunction.scala
+++ b/streaming/src/main/scala/org/apache/gearpump/streaming/dsl/scalaapi/functions/FlatMapFunction.scala
@@ -93,8 +93,8 @@
  * Transforms one input into zero or more outputs of possibly different types.
  * This Scala version of FlatMapFunction returns a TraversableOnce.
  *
- * @param T Input value type
- * @param R Output value type
+ * @tparam T Input value type
+ * @tparam R Output value type
  */
 abstract class FlatMapFunction[T, R] extends SerializableFunction {