MockServletConfig: Fix warning about unchecked conversion of Enumeration

Change-Id: Ic5ce6d220e3b644032819ce4b2f31c669be1cdb9
Signed-off-by: David Pursehouse <david.pursehouse@sonymobile.com>

org.eclipse.jgit.junit.http/src/org/eclipse/jgit/junit/http/MockServletConfig.java

@@ -62,7 +62,7 @@ public class MockServletConfig implements ServletConfig {
 		return parameters.get(name);
 	}
 
-	public Enumeration getInitParameterNames() {
+	public Enumeration<String> getInitParameterNames() {
 		final Iterator<String> i = parameters.keySet().iterator();
 		return new Enumeration<String>() {
 			public boolean hasMoreElements() {