BATCH-2711: Fix JobParameterBuilder not to overwrite new parameters with old ones

spring-batch-core/src/main/java/org/springframework/batch/core/JobParametersBuilder.java

@@ -41,6 +41,7 @@
  * @author Michael Minella
  * @author Glenn Renfro
  * @author Mahmoud Ben Hassine
+ * @author Minhyeok Jeong
  * @since 1.0
  * @see JobParameters
  * @see JobParameter
@@ -224,15 +225,29 @@ public JobParametersBuilder addParameter(String key, JobParameter jobParameter)
 	}
 
 	/**
-	 * Copy job parameters into the current state.
-	 * @param jobParameters parameters to copy in
+	 * Add job parameters into the current parameter map. If the map previously
+	 * contained a mapping for the key, the old value is replaced.
+	 *
+	 * @param jobParameters parameters to add to
 	 * @return a reference to this object.
 	 */
 	public JobParametersBuilder addJobParameters(JobParameters jobParameters) {
 		Assert.notNull(jobParameters, "jobParameters must not be null");
-
 		this.parameterMap.putAll(jobParameters.getParameters());
+		return this;
+	}
 
+	/**
+	 * Add job parameters into the current parameter map. If the map previously
+	 * contained a mapping for the key, the new value is ignored.
+	 *
+	 * @param jobParameters parameters to add to
+	 * @return a reference to this object.
+	 */
+	public JobParametersBuilder addJobParametersIfAbsent(JobParameters jobParameters) {
+		Assert.notNull(jobParameters, "jobParameters must not be null");
+		jobParameters.getParameters().forEach(
+				(key, value) -> this.parameterMap.putIfAbsent(key, value));
 		return this;
 	}
 
@@ -282,7 +297,7 @@ else if (incrementer != null) {
 			}
 		}
 
-		this.parameterMap = addJobParameters(nextParameters)
+		this.parameterMap = addJobParametersIfAbsent(nextParameters)
 								.toJobParameters()
 								.getParameters();
 		return this;

spring-batch-core/src/test/java/org/springframework/batch/core/JobParametersBuilderTests.java

@@ -18,6 +18,7 @@
 import java.util.ArrayList;
 import java.util.Date;
 import java.util.Iterator;
+import java.util.LinkedHashMap;
 import java.util.List;
 import java.util.Map;
 import java.util.Properties;
@@ -40,7 +41,7 @@
  * @author Michael Minella
  * @author Glenn Renfro
  * @author Mahmoud Ben Hassine
- *
+ * @author Minhyeok Jeong
  */
 public class JobParametersBuilderTests {
 
@@ -82,9 +83,31 @@ public void testAddingExistingJobParameters() {
 				.addJobParameters(params2)
 				.toJobParameters();
 
-		assertEquals(finalParams.getString("foo"), "baz");
-		assertEquals(finalParams.getString("bar"), "baz");
-		assertEquals(finalParams.getString("baz"), "quix");
+		assertEquals("baz", finalParams.getString("foo"));
+		assertEquals("baz", finalParams.getString("bar"));
+		assertEquals("quix", finalParams.getString("baz"));
+	}
+
+	@Test
+	public void testAddingExistingJobParametersIfAbsent() {
+		JobParameters params1 = new JobParametersBuilder()
+				.addString("foo", "bar")
+				.addString("bar", "baz")
+				.toJobParameters();
+
+		JobParameters params2 = new JobParametersBuilder()
+				.addString("foo", "baz")
+				.toJobParameters();
+
+		JobParameters finalParams = new JobParametersBuilder()
+				.addString("baz", "quix")
+				.addJobParametersIfAbsent(params1)
+				.addJobParametersIfAbsent(params2)
+				.toJobParameters();
+
+		assertEquals("bar", finalParams.getString("foo"));
+		assertEquals("baz", finalParams.getString("bar"));
+		assertEquals("quix", finalParams.getString("baz"));
 	}
 
 	@Test
@@ -265,11 +288,16 @@ private void baseJobParametersVerify(JobParameters parameters, int paramCount) {
 	}
 
 	private JobExecution getJobExecution(JobInstance jobInstance, BatchStatus batchStatus) {
-		JobExecution jobExecution = new JobExecution(jobInstance, 1L, null, "TestConfig");
+		Map<String, JobParameter> parameters = new LinkedHashMap<>();
+		parameters.put("STRING", new JobParameter("previous value"));
+		JobParameters jobParameters = new JobParameters(parameters);
+
+		JobExecution jobExecution = new JobExecution(jobInstance, 1L, jobParameters, "TestConfig");
+
 		if(batchStatus != null) {
 			jobExecution.setStatus(batchStatus);
 		}
-		return jobExecution;
 
+		return jobExecution;
 	}
 }