[SPARK-15134][EXAMPLE] Indent SparkSession builder patterns and update binary_classification_metrics_example.py

## What changes were proposed in this pull request?

This issue addresses the comments in SPARK-15031 and also fix java-linter errors.
- Use multiline format in SparkSession builder patterns.
- Update `binary_classification_metrics_example.py` to use `SparkSession`.
- Fix Java Linter errors (in SPARK-13745, SPARK-15031, and so far)

## How was this patch tested?

After passing the Jenkins tests and run `dev/lint-java` manually.

Author: Dongjoon Hyun <dongjoon@apache.org>

Closes #12911 from dongjoon-hyun/SPARK-15134.

1 files changed, 4 insertions, 1 deletions

diff --git a/examples/src/main/python/ml/decision_tree_regression_example.py b/examples/src/main/python/ml/decision_tree_regression_example.py
index 9e8cb382a9..b734d4974a 100644
--- a/examples/src/main/python/ml/decision_tree_regression_example.py
+++ b/examples/src/main/python/ml/decision_tree_regression_example.py
@@ -29,7 +29,10 @@ from pyspark.ml.evaluation import RegressionEvaluator
 from pyspark.sql import SparkSession
 
 if __name__ == "__main__":
-    spark = SparkSession.builder.appName("decision_tree_classification_example").getOrCreate()
+    spark = SparkSession\
+        .builder\
+        .appName("decision_tree_classification_example")\
+        .getOrCreate()
 
     # $example on$
     # Load the data stored in LIBSVM format as a DataFrame.