cleanup unused imports

Author: JacksonTian

aliyun-java-sdk-core/src/main/java/com/aliyuncs/auth/V3SignatureComposer.java

@@ -15,7 +15,6 @@ public class V3SignatureComposer implements ISignatureComposer {
     protected final static String QUERY_SEPARATOR = "&";
     protected final static String HEADER_SEPARATOR = "\n";
     private final static String DELIMITER = ";";
-    private final static String UTF8 = "UTF-8";
     private static ISignatureComposer composer = null;
     private final static String SIGNED_HEADERS = "signedHeaders";
     private final static String CANONICAL_HEADERS = "canonicalHeaders";

aliyun-java-sdk-core/src/main/java/com/aliyuncs/auth/signers/HmacSHA1Signer.java

@@ -2,11 +2,9 @@
 
 import com.aliyuncs.auth.AlibabaCloudCredentials;
 import com.aliyuncs.auth.Signer;
-import org.bouncycastle.jce.provider.BouncyCastleProvider;
 
 import java.io.UnsupportedEncodingException;
 import java.security.InvalidKeyException;
-import java.security.MessageDigest;
 import java.security.NoSuchAlgorithmException;
 
 import javax.crypto.Mac;

aliyun-java-sdk-core/src/main/java/com/aliyuncs/policy/retry/pattern/AliyunThrottlingPattern.java

@@ -10,10 +10,7 @@ public class AliyunThrottlingPattern implements Pattern {
 
     private Map<String, String> throttlingMap = new HashMap<String, String>();
     private static String Remain = "remain";
-    private static String Limit = "limit";
-    private static String Time = "time";
     private static String TimeLeft = "timeleft";
-    private static String Reset = "reset";
     private AliyunThrottlingPattern anotherPattern;
 
     public AliyunThrottlingPattern(String content) {

aliyun-java-sdk-core/src/main/java/com/aliyuncs/policy/retry/pattern/SimplePattern.java

@@ -7,7 +7,7 @@ public class SimplePattern implements Pattern {
     private SimplePattern anotherPattern;
 
     public SimplePattern(String context) {
-        this.context = context;
+        SimplePattern.context = context;
     }
 
     public String getContext() {

aliyun-java-sdk-core/src/test/java/com/aliyuncs/auth/StaticCredentialsProviderTest.java

@@ -2,8 +2,6 @@
 
 import static org.mockito.Mockito.mock;
 
-import com.aliyuncs.DefaultAcsClient;
-import com.aliyuncs.profile.DefaultProfile;
 import org.junit.Assert;
 import org.junit.Test;
 import org.mockito.Mockito;

aliyun-java-sdk-core/src/test/java/com/aliyuncs/auth/V3SignatureComposerTest.java

@@ -8,8 +8,6 @@
 import org.powermock.core.classloader.annotations.PrepareForTest;
 import org.powermock.modules.junit4.PowerMockRunner;
 
-import java.io.UnsupportedEncodingException;
-import java.security.NoSuchAlgorithmException;
 import java.util.HashMap;
 import java.util.Map;