docs(tutorials): Add README, other small fixes to JsonWriterDefaultStream tutorial (#1504)

- Add a readme file
- Fix the POM file for the current directory structure
- Change one schema field in the sample

Author: VeronicaWasson

tutorials/JsonWriterDefaultStream/JsonWriterDefaultStream.java

@@ -67,7 +67,7 @@ public static void createDestinationTable(
                 .build(),
             Field.of("author", StandardSQLTypeName.STRING),
             Field.of("committer", StandardSQLTypeName.STRING),
-            Field.of("time_sec", StandardSQLTypeName.INT64),
+            Field.of("ts", StandardSQLTypeName.DATETIME),
             Field.of("subject", StandardSQLTypeName.STRING),
             Field.of("message", StandardSQLTypeName.STRING),
             Field.of("repo_name", StandardSQLTypeName.STRING));

tutorials/JsonWriterDefaultStream/README.md

@@ -0,0 +1,21 @@
+# BigQuery Write API streaming tutorial
+
+This sample shows how to stream data from a JSON source into BigQuery by using
+the [BigQuery Write API](https://cloud.google.com/bigquery/docs/write-api) with
+the default stream.
+
+## Usage
+
+Download the
+[sample data file](https://storage.googleapis.com/cloud-samples-data/bigquery/tutorials/github.json).
+
+From this directory, run:
+
+```
+mvn compile exec:java \
+  -Dexec.mainClass=com.example.bigquerystorage.JsonWriterDefaultStream \
+  -Dexec.args="project_id dataset table filepath`
+```
+
+where `file_path` is the path to the JSON data file.
+

tutorials/JsonWriterDefaultStream/pom.xml

@@ -57,8 +57,8 @@
             </goals>
             <configuration>
               <sources>
-                <source>src/main/java</source>
-                <source>../snippets/src/main/java/com/example/bigquerystorage</source>
+                <source>.</source>
+                <source>../../samples/snippets/src/main/java/com/example/bigquerystorage</source>
               </sources>
             </configuration>
           </execution>
@@ -81,4 +81,4 @@
       </plugin>
     </plugins>
   </build>
-</project>
+</project>