Enforce no illegal throws via Checkstyle

Also remove a stray unused import.

core/src/main/java/org/jclouds/concurrent/internal/SyncProxy.java

@@ -134,7 +134,7 @@ public class SyncProxy implements InvocationHandler {
       return methodNanos;
    }
 
-   public Object invoke(Object o, Method method, Object[] args) throws Throwable {
+   public Object invoke(Object o, Method method, Object[] args) throws Exception {
       if (method.getName().equals("equals")) {
          return this.equals(o);
       } else if (method.getName().equals("hashCode")) {

core/src/main/java/org/jclouds/rest/config/BinderUtils.java

@@ -99,7 +99,7 @@ public class BinderUtils {
       return (T) Proxy.newProxyInstance(clazz.getClassLoader(), new Class<?>[] { clazz }, new InvocationHandler() {
 
          @Override
-         public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
+         public Object invoke(Object proxy, Method method, Object[] args) {
             return null;
          }
 

core/src/main/java/org/jclouds/rest/internal/AsyncRestClientProxy.java

@@ -133,7 +133,7 @@ public class AsyncRestClientProxy<T> implements InvocationHandler {
 
    };
 
-   public Object invoke(Object o, Method method, Object[] args) throws Throwable {
+   public Object invoke(Object o, Method method, Object[] args) throws ExecutionException {
       if (method.getName().equals("equals")) {
          return this.equals(o);
       } else if (method.getName().equals("toString")) {

labs/virtualbox/src/main/java/org/jclouds/virtualbox/functions/YamlImagesFromFileConfig.java

@@ -23,7 +23,6 @@ import static com.google.common.base.Preconditions.checkNotNull;
 
 import java.io.File;
 import java.io.IOException;
-import java.io.InputStreamReader;
 
 import javax.inject.Inject;
 import javax.inject.Named;

resources/checkstyle.xml

@@ -6,6 +6,7 @@
     <module name="NewlineAtEndOfFile"/>
     <module name="TreeWalker">
         <module name="EmptyStatement"/>
+        <module name="IllegalThrows"/>
         <module name="LineLength">
             <property name="ignorePattern" value="^import\s.*;$"/>
             <property name="max" value="120"/>