Prefer static imports for Preconditions

src/main/java/org/gaul/s3proxy/S3ErrorCode.java

@@ -16,10 +16,11 @@
 
 package org.gaul.s3proxy;
 
+import static com.google.common.base.Preconditions.checkNotNull;
+
 import javax.servlet.http.HttpServletResponse;
 
 import com.google.common.base.CaseFormat;
-import com.google.common.base.Preconditions;
 
 /**
  * List of S3 error codes.  Reference:
@@ -63,7 +64,7 @@ enum S3ErrorCode {
         this.errorCode = CaseFormat.UPPER_UNDERSCORE.to(CaseFormat.UPPER_CAMEL,
                 name());
         this.httpStatusCode = httpStatusCode;
-        this.message = Preconditions.checkNotNull(message);
+        this.message = checkNotNull(message);
     }
 
     public String getErrorCode() {

src/main/java/org/gaul/s3proxy/S3Proxy.java

@@ -16,6 +16,9 @@
 
 package org.gaul.s3proxy;
 
+import static com.google.common.base.Preconditions.checkArgument;
+import static com.google.common.base.Preconditions.checkNotNull;
+
 import java.io.File;
 import java.io.FileInputStream;
 import java.io.InputStream;
@@ -23,7 +26,6 @@ import java.net.URI;
 import java.util.Properties;
 
 import com.google.common.base.Optional;
-import com.google.common.base.Preconditions;
 import com.google.common.base.Strings;
 import com.google.common.collect.ImmutableList;
 import com.google.inject.Module;
@@ -56,11 +58,12 @@ public final class S3Proxy {
     public S3Proxy(BlobStore blobStore, URI endpoint, String identity,
             String credential, String keyStorePath, String keyStorePassword,
             boolean forceMultiPartUpload, Optional<String> virtualHost) {
-        Preconditions.checkNotNull(blobStore);
-        Preconditions.checkNotNull(endpoint);
+        checkNotNull(blobStore);
+        checkNotNull(endpoint);
         // TODO: allow service paths?
-        Preconditions.checkArgument(endpoint.getPath().isEmpty(),
+        checkArgument(endpoint.getPath().isEmpty(),
                 "endpoint path must be empty, was: " + endpoint.getPath());
+        checkNotNull(virtualHost);
 
         server = new Server();
         HttpConnectionFactory httpConnectionFactory =

src/main/java/org/gaul/s3proxy/S3ProxyHandler.java

@@ -16,6 +16,9 @@
 
 package org.gaul.s3proxy;
 
+import static com.google.common.base.Preconditions.checkArgument;
+import static com.google.common.base.Preconditions.checkNotNull;
+
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.OutputStream;
@@ -50,7 +53,6 @@ import javax.xml.stream.XMLStreamReader;
 import javax.xml.stream.XMLStreamWriter;
 
 import com.google.common.base.Optional;
-import com.google.common.base.Preconditions;
 import com.google.common.base.Strings;
 import com.google.common.base.Throwables;
 import com.google.common.collect.ImmutableMap;
@@ -133,13 +135,13 @@ final class S3ProxyHandler extends AbstractHandler {
 
     S3ProxyHandler(BlobStore blobStore, String identity, String credential,
             boolean forceMultiPartUpload, Optional<String> virtualHost) {
-        this.blobStore = Preconditions.checkNotNull(blobStore);
+        this.blobStore = checkNotNull(blobStore);
         this.blobStoreType =
                 blobStore.getContext().unwrap().getProviderMetadata().getId();
         this.identity = identity;
         this.credential = credential;
         this.forceMultiPartUpload = forceMultiPartUpload;
-        this.virtualHost = Preconditions.checkNotNull(virtualHost);
+        this.virtualHost = checkNotNull(virtualHost);
         xmlOutputFactory.setProperty("javax.xml.stream.isRepairingNamespaces",
                 Boolean.FALSE);
     }
@@ -1222,7 +1224,7 @@ final class S3ProxyHandler extends AbstractHandler {
     private void sendSimpleErrorResponse(HttpServletResponse response,
             S3ErrorCode code, String element, String characters)
             throws IOException {
-        Preconditions.checkArgument(!(element == null ^ characters == null),
+        checkArgument(!(element == null ^ characters == null),
                 "Must specify neither or both element and characters");
         logger.debug("{} {} {}", code, element, characters);
 

src/main/resources/checkstyle.xml

@@ -17,7 +17,7 @@
     <module name="AvoidNestedBlocks"/>
     <module name="AvoidStarImport"/>
     <module name="AvoidStaticImport">
-      <property name="excludes" value="org.assertj.core.api.Assertions.assertThat,org.junit.Assert.fail"/>
+      <property name="excludes" value="com.google.common.base.Preconditions.checkArgument,com.google.common.base.Preconditions.checkNotNull,com.google.common.base.Preconditions.checkState,org.assertj.core.api.Assertions.assertThat,org.junit.Assert.fail"/>
     </module>
     <module name="ClassTypeParameterName"/>
     <module name="CovariantEquals"/>