[SPARK-16294][SQL] Labelling support for the include_example Jekyll plugin

## What changes were proposed in this pull request?

This PR adds labelling support for the `include_example` Jekyll plugin, so that we may split a single source file into multiple line blocks with different labels, and include them in multiple code snippets in the generated HTML page.

## How was this patch tested?

Manually tested.

<img width="923" alt="screenshot at jun 29 19-53-21" src="https://cloud.githubusercontent.com/assets/230655/16451099/66a76db2-3e33-11e6-84fb-63104c2f0688.png">

Author: Cheng Lian <lian@databricks.com>

Closes #13972 from liancheng/include-example-with-labels.

1 files changed, 5 insertions, 0 deletions

diff --git a/examples/src/main/java/org/apache/spark/examples/sql/JavaSparkSQL.java b/examples/src/main/java/org/apache/spark/examples/sql/JavaSparkSQL.java
index e512979ac7..7fc6c007b6 100644
--- a/examples/src/main/java/org/apache/spark/examples/sql/JavaSparkSQL.java
+++ b/examples/src/main/java/org/apache/spark/examples/sql/JavaSparkSQL.java
@@ -26,7 +26,9 @@ import org.apache.spark.api.java.function.Function;
 
 import org.apache.spark.sql.Dataset;
 import org.apache.spark.sql.Row;
+// $example on:init_session$
 import org.apache.spark.sql.SparkSession;
+// $example off:init_session$
 
 public class JavaSparkSQL {
   public static class Person implements Serializable {
@@ -51,10 +53,13 @@ public class JavaSparkSQL {
   }
 
   public static void main(String[] args) throws Exception {
+    // $example on:init_session$
     SparkSession spark = SparkSession
       .builder()
       .appName("JavaSparkSQL")
+      .config("spark.some.config.option", "some-value")
       .getOrCreate();
+    // $example off:init_session$
 
     System.out.println("=== Data source: RDD ===");
     // Load a text file and convert each line to a Java Bean.