Fix [serial] compiler warnings

Fix serialization warnings by applying @SuppressWarnings("serial")
when appropriate.

In certain cases and for unknown reasons, a correctly-placed
@SuppressWarnings("serial") annotation will fix the warning at the
javac level (i.e. the Gradle command-line), but will produce an
"unnecessary @SuppressWarnings" warning within Eclipse. In these
cases, a private static final serialVersionUID field has been added
with the default value of 1L.

spring-oxm/src/main/java/org/springframework/oxm/MarshallingException.java

@@ -25,6 +25,7 @@ package org.springframework.oxm;
  * @see MarshallingFailureException
  * @see UnmarshallingFailureException
  */
+@SuppressWarnings("serial")
 public abstract class MarshallingException extends XmlMappingException {
 
 	/**

spring-oxm/src/main/java/org/springframework/oxm/MarshallingFailureException.java

@@ -22,6 +22,7 @@ package org.springframework.oxm;
  * @author Arjen Poutsma
  * @since 3.0
  */
+@SuppressWarnings("serial")
 public class MarshallingFailureException extends MarshallingException {
 
 	/**

spring-oxm/src/main/java/org/springframework/oxm/UncategorizedMappingException.java

@@ -22,6 +22,7 @@ package org.springframework.oxm;
  * @author Arjen Poutsma
  * @since 3.0
  */
+@SuppressWarnings("serial")
 public class UncategorizedMappingException extends XmlMappingException {
 
 	/**

spring-oxm/src/main/java/org/springframework/oxm/UnmarshallingFailureException.java

@@ -22,6 +22,7 @@ package org.springframework.oxm;
  * @author Arjen Poutsma
  * @since 3.0
  */
+@SuppressWarnings("serial")
 public class UnmarshallingFailureException extends MarshallingException {
 
 	/**

spring-oxm/src/main/java/org/springframework/oxm/ValidationFailureException.java

@@ -22,6 +22,7 @@ package org.springframework.oxm;
  * @author Arjen Poutsma
  * @since 3.0
  */
+@SuppressWarnings("serial")
 public class ValidationFailureException extends XmlMappingException {
 
 	/**

spring-oxm/src/main/java/org/springframework/oxm/XmlMappingException.java

@@ -24,6 +24,7 @@ import org.springframework.core.NestedRuntimeException;
  * @author Arjen Poutsma
  * @since 3.0
  */
+@SuppressWarnings("serial")
 public abstract class XmlMappingException extends NestedRuntimeException {
 
 	/**

spring-oxm/src/main/java/org/springframework/oxm/castor/CastorMappingException.java

@@ -24,6 +24,7 @@ import org.springframework.oxm.XmlMappingException;
  * @author Juergen Hoeller
  * @since 3.0
  */
+@SuppressWarnings("serial")
 public class CastorMappingException extends XmlMappingException {
 
 	/**