Replace StringBuffe with StringBuilder

Issues: SWF-1532

spring-binding/src/main/java/org/springframework/binding/expression/support/CompositeStringExpression.java

@@ -41,11 +41,11 @@ public class CompositeStringExpression implements Expression {
 	}
 
 	public Object getValue(Object context) throws EvaluationException {
-		StringBuffer buffer = new StringBuffer(128);
+		StringBuilder value = new StringBuilder(128);
 		for (Expression expression : expressions) {
-			buffer.append(expression.getValue(context));
+			value.append(expression.getValue(context));
 		}
-		return buffer.toString();
+		return value.toString();
 	}
 
 	public void setValue(Object context, Object value) throws EvaluationException {

spring-binding/src/main/java/org/springframework/binding/method/MethodKey.java

@@ -199,7 +199,7 @@ public class MethodKey implements Serializable {
 	 * Convenience method that returns the parameter types describing the signature of the method as a string.
 	 */
 	private String parameterTypesString() {
-		StringBuffer parameterTypesString = new StringBuffer();
+		StringBuilder parameterTypesString = new StringBuilder();
 		for (int i = 0; i < parameterTypes.length; i++) {
 			if (parameterTypes[i] == null) {
 				parameterTypesString.append("<any>");

spring-binding/src/test/java/org/springframework/binding/convert/service/StaticConversionExecutorImplTests.java

@@ -51,7 +51,7 @@ public class StaticConversionExecutorImplTests extends TestCase {
 
 	public void testIllegalType() {
 		try {
-			conversionExecutor.execute(new StringBuffer());
+			conversionExecutor.execute(new StringBuilder());
 			fail();
 		} catch (ConversionExecutionException e) {
 			// expected