Improve error messages in JobParametersBuilder

Resolves #4581

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

@@ -105,6 +105,7 @@ public JobParametersBuilder addString(String key, @NonNull String parameter) {
 	 * @return a reference to this object.
 	 */
 	public JobParametersBuilder addString(String key, @NonNull String parameter, boolean identifying) {
+		Assert.notNull(parameter, "Value for parameter '" + key + "' must not be null");
 		this.parameterMap.put(key, new JobParameter<>(parameter, String.class, identifying));
 		return this;
 	}
@@ -128,6 +129,7 @@ public JobParametersBuilder addDate(String key, @NonNull Date parameter) {
 	 * @return a reference to this object.
 	 */
 	public JobParametersBuilder addDate(String key, @NonNull Date parameter, boolean identifying) {
+		Assert.notNull(parameter, "Value for parameter '" + key + "' must not be null");
 		this.parameterMap.put(key, new JobParameter<>(parameter, Date.class, identifying));
 		return this;
 	}
@@ -151,6 +153,7 @@ public JobParametersBuilder addLocalDate(String key, @NonNull LocalDate paramete
 	 * @return a reference to this object.
 	 */
 	public JobParametersBuilder addLocalDate(String key, @NonNull LocalDate parameter, boolean identifying) {
+		Assert.notNull(parameter, "Value for parameter '" + key + "' must not be null");
 		this.parameterMap.put(key, new JobParameter<>(parameter, LocalDate.class, identifying));
 		return this;
 	}
@@ -174,6 +177,7 @@ public JobParametersBuilder addLocalTime(String key, @NonNull LocalTime paramete
 	 * @return a reference to this object.
 	 */
 	public JobParametersBuilder addLocalTime(String key, @NonNull LocalTime parameter, boolean identifying) {
+		Assert.notNull(parameter, "Value for parameter '" + key + "' must not be null");
 		this.parameterMap.put(key, new JobParameter<>(parameter, LocalTime.class, identifying));
 		return this;
 	}
@@ -197,6 +201,7 @@ public JobParametersBuilder addLocalDateTime(String key, @NonNull LocalDateTime
 	 * @return a reference to this object.
 	 */
 	public JobParametersBuilder addLocalDateTime(String key, @NonNull LocalDateTime parameter, boolean identifying) {
+		Assert.notNull(parameter, "Value for parameter '" + key + "' must not be null");
 		this.parameterMap.put(key, new JobParameter<>(parameter, LocalDateTime.class, identifying));
 		return this;
 	}
@@ -220,6 +225,7 @@ public JobParametersBuilder addLong(String key, @NonNull Long parameter) {
 	 * @return a reference to this object.
 	 */
 	public JobParametersBuilder addLong(String key, @NonNull Long parameter, boolean identifying) {
+		Assert.notNull(parameter, "Value for parameter '" + key + "' must not be null");
 		this.parameterMap.put(key, new JobParameter<>(parameter, Long.class, identifying));
 		return this;
 	}
@@ -243,6 +249,7 @@ public JobParametersBuilder addDouble(String key, @NonNull Double parameter) {
 	 * @return a reference to this object.
 	 */
 	public JobParametersBuilder addDouble(String key, @NonNull Double parameter, boolean identifying) {
+		Assert.notNull(parameter, "Value for parameter '" + key + "' must not be null");
 		this.parameterMap.put(key, new JobParameter<>(parameter, Double.class, identifying));
 		return this;
 	}
@@ -285,27 +292,28 @@ public JobParametersBuilder addJobParameter(String key, JobParameter<?> jobParam
 	/**
 	 * Add a job parameter.
 	 * @param name the name of the parameter
-	 * @param value the value of the parameter
+	 * @param value the value of the parameter. Must not be {@code null}.
 	 * @param type the type of the parameter
 	 * @param identifying true if the parameter is identifying. false otherwise
 	 * @return a reference to this object.
 	 * @param <T> the type of the parameter
 	 * @since 5.0
 	 */
-	public <T> JobParametersBuilder addJobParameter(String name, T value, Class<T> type, boolean identifying) {
+	public <T> JobParametersBuilder addJobParameter(String name, @NonNull T value, Class<T> type, boolean identifying) {
+		Assert.notNull(value, "Value for parameter '" + name + "' must not be null");
 		return addJobParameter(name, new JobParameter<>(value, type, identifying));
 	}
 
 	/**
 	 * Add an identifying job parameter.
 	 * @param name the name of the parameter
-	 * @param value the value of the parameter
+	 * @param value the value of the parameter. Must not be {@code null}.
 	 * @param type the type of the parameter
 	 * @return a reference to this object.
 	 * @param <T> the type of the parameter
 	 * @since 5.0
 	 */
-	public <T> JobParametersBuilder addJobParameter(String name, T value, Class<T> type) {
+	public <T> JobParametersBuilder addJobParameter(String name, @NonNull T value, Class<T> type) {
 		return addJobParameter(name, value, type, true);
 	}
 

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2008-2023 the original author or authors.
+ * Copyright 2008-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -22,6 +22,7 @@
 import java.util.Map;
 import java.util.Set;
 
+import org.junit.jupiter.api.Assertions;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 
@@ -85,6 +86,13 @@ void testAddingExistingJobParameters() {
 		assertEquals(finalParams.getString("baz"), "quix");
 	}
 
+	@Test
+	void testAddingNullJobParameters() {
+		IllegalArgumentException exception = assertThrows(IllegalArgumentException.class,
+				() -> new JobParametersBuilder().addString("foo", null).toJobParameters());
+		Assertions.assertEquals("Value for parameter 'foo' must not be null", exception.getMessage());
+	}
+
 	@Test
 	void testNonIdentifyingParameters() {
 		this.parametersBuilder.addDate("SCHEDULE_DATE", date, false);