[FLINK-4595] Close FileOutputStream in ParameterTool

This closes #2478

flink-java/src/main/java/org/apache/flink/api/java/utils/ParameterTool.java

@@ -31,6 +31,7 @@ import java.io.FileInputStream;
 import java.io.FileNotFoundException;
 import java.io.FileOutputStream;
 import java.io.IOException;
+import java.io.OutputStream;
 import java.io.Serializable;
 import java.util.Arrays;
 import java.util.HashMap;
@@ -523,7 +524,9 @@ public class ParameterTool extends ExecutionConfig.GlobalJobParameters implement
 		}
 		Properties defaultProps = new Properties();
 		defaultProps.putAll(this.defaultData);
-		defaultProps.store(new FileOutputStream(file), "Default file created by Flink's ParameterUtil.createPropertiesFile()");
+		try (final OutputStream out = new FileOutputStream(file)) {
+			defaultProps.store(out, "Default file created by Flink's ParameterUtil.createPropertiesFile()");
+		}
 	}
 
 	@Override

flink-java/src/test/java/org/apache/flink/api/java/utils/ParameterToolTest.java

@@ -29,6 +29,7 @@ import java.io.File;
 import java.io.FileInputStream;
 import java.io.FileOutputStream;
 import java.io.IOException;
+import java.io.OutputStream;
 import java.util.Map;
 import java.util.Properties;
 
@@ -118,7 +119,9 @@ public class ParameterToolTest {
 		Properties props = new Properties();
 		props.setProperty("input", "myInput");
 		props.setProperty("expectedCount", "15");
-		props.store(new FileOutputStream(propertiesFile), "Test properties");
+		try (final OutputStream out = new FileOutputStream(propertiesFile)) {
+			props.store(out, "Test properties");
+		}
 		ParameterTool parameter = ParameterTool.fromPropertiesFile(propertiesFile.getAbsolutePath());
 		Assert.assertEquals(2, parameter.getNumberOfParameters());
 		validate(parameter);