Ensure simple boolean expressions via Checkstyle

apis/s3/src/main/java/org/jclouds/s3/filters/RequestAuthorizeSignature.java

@@ -242,7 +242,7 @@ public class RequestAuthorizeSignature implements HttpRequestFilter, RequestSign
          char separator = '?';
          for (String paramName : Ordering.natural().sortedCopy(params.keySet())) {
             // Skip any parameters that aren't part of the canonical signed string
-            if (SIGNED_PARAMETERS.contains(paramName) == false)
+            if (!SIGNED_PARAMETERS.contains(paramName))
                continue;
             toSign.append(separator).append(paramName);
             String paramValue = get(params.get(paramName), 0);

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

@@ -160,7 +160,7 @@ public class NodeCreator implements Function<NodeSpec, NodeAndInitialCredentials
        machineUtils.runScriptOnNode(partialNodeMetadata, new DeleteGShadowLock(), RunScriptOptions.NONE);
 
       if(optionalNatIfaceCard.isPresent())
-         checkState(networkUtils.enableNetworkInterface(partialNodeMetadata, optionalNatIfaceCard.get()) == true, 
+         checkState(networkUtils.enableNetworkInterface(partialNodeMetadata, optionalNatIfaceCard.get()),
          "cannot enable Nat Interface");
       
       LoginCredentials credentials = partialNodeMetadata.getCredentials();

resources/checkstyle.xml

@@ -13,6 +13,7 @@
         </module>
         <module name="ModifierOrder"/>
         <module name="MultipleVariableDeclarations"/>
+        <module name="SimplifyBooleanExpression"/>
         <module name="UnusedImports"/>
     </module>
     <module name="RegexpMultiline">