Improve formatting of IllegalArgumentException message thrown by DefaultExecutionContextSerializer

spring-batch-core/src/main/java/org/springframework/batch/core/repository/dao/DefaultExecutionContextSerializer.java

@@ -60,8 +60,8 @@ public class DefaultExecutionContextSerializer implements ExecutionContextSerial
 			Assert.notNull(value, "A null value was found");
 			if (!(value instanceof Serializable)) {
 				throw new IllegalArgumentException(
-						"Value: [ " + value + "must be serializable."
-						+ "Object of class [" + value.getClass().getName()
+						"Value: [" + value + "] must be serializable. "
+						+ "Object of class: [" + value.getClass().getName()
 						+ "] must be an instance of " + Serializable.class);
 			}
 		}