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-expression/src/test/java/org/springframework/expression/spel/ConstructorInvocationTests.java

@@ -49,6 +49,7 @@ public class ConstructorInvocationTests extends ExpressionTestCase {
 		evaluateAndCheckError("new FooBar()",SpelMessage.CONSTRUCTOR_INVOCATION_PROBLEM);
 	}
 
+	@SuppressWarnings("serial")
 	static class TestException extends Exception {
 
 	}

spring-expression/src/test/java/org/springframework/expression/spel/testresources/Inventor.java

@@ -111,6 +111,7 @@ public class Inventor {
 		return valueIn;
 	}
 
+	@SuppressWarnings("serial")
 	static class TestException extends Exception {}
 
 	public String throwException(PlaceOfBirth pob) {