Add Checkstyle and configure it for star imports. Remove star imports so Checkstyle passes

Author: J Plasmeier

pom.xml

@@ -134,6 +134,21 @@
           </execution>
         </executions>
       </plugin>
+      <plugin>
+        <groupId>org.apache.maven.plugins</groupId>
+        <artifactId>maven-checkstyle-plugin</artifactId>
+        <version>3.2.0</version>
+        <configuration>
+          <configLocation>utils/checkstyle.xml</configLocation>
+        </configuration>
+        <executions>
+          <execution>
+            <goals>
+              <goal>check</goal>
+            </goals>
+          </execution>
+        </executions>
+      </plugin>
     </plugins>
   </build>
 

src/main/java/software/amazon/encryption/s3/S3EncryptionClient.java

@@ -1,6 +1,6 @@
 package software.amazon.encryption.s3;
 
-import java.security.*;
+import java.security.KeyPair;
 import java.util.Map;
 import java.util.function.Consumer;
 import javax.crypto.SecretKey;
@@ -17,7 +17,13 @@
 import software.amazon.awssdk.services.s3.model.PutObjectResponse;
 import software.amazon.encryption.s3.internal.GetEncryptedObjectPipeline;
 import software.amazon.encryption.s3.internal.PutEncryptedObjectPipeline;
-import software.amazon.encryption.s3.materials.*;
+import software.amazon.encryption.s3.materials.AesKeyring;
+import software.amazon.encryption.s3.materials.CryptographicMaterialsManager;
+import software.amazon.encryption.s3.materials.DefaultCryptoMaterialsManager;
+import software.amazon.encryption.s3.materials.Keyring;
+import software.amazon.encryption.s3.materials.KmsKeyring;
+import software.amazon.encryption.s3.materials.PartialRsaKeyPair;
+import software.amazon.encryption.s3.materials.RsaKeyring;
 
 /**
  * This client is a drop-in replacement for the S3 client. It will automatically encrypt objects

src/main/java/software/amazon/encryption/s3/materials/RsaKeyring.java

@@ -1,7 +1,9 @@
 package software.amazon.encryption.s3.materials;
 
 import java.nio.charset.StandardCharsets;
-import java.security.*;
+import java.security.GeneralSecurityException;
+import java.security.Key;
+import java.security.SecureRandom;
 import java.security.spec.MGF1ParameterSpec;
 import java.util.Arrays;
 import java.util.HashMap;
@@ -18,8 +20,6 @@
  */
 public class RsaKeyring extends S3Keyring {
 
-    private static final String KEY_ALGORITHM = "RSA";
-
     private final PartialRsaKeyPair _partialRsaKeyPair;
 
     private final DecryptDataKeyStrategy _rsaEcbStrategy = new DecryptDataKeyStrategy() {
@@ -71,7 +71,7 @@ public String keyProviderInfo() {
 
         @Override
         public byte[] encryptDataKey(SecureRandom secureRandom,
-                EncryptionMaterials materials) throws GeneralSecurityException {
+                                     EncryptionMaterials materials) throws GeneralSecurityException {
             final Cipher cipher = Cipher.getInstance(CIPHER_ALGORITHM);
             cipher.init(Cipher.WRAP_MODE, _partialRsaKeyPair.getPublicKey(), OAEP_PARAMETER_SPEC, secureRandom);
 

src/test/java/software/amazon/encryption/s3/S3EncryptionClientTest.java

@@ -5,7 +5,6 @@
 import software.amazon.awssdk.core.sync.RequestBody;
 import software.amazon.awssdk.services.s3.S3Client;
 import software.amazon.awssdk.services.s3.model.GetObjectResponse;
-import software.amazon.awssdk.services.s3.model.PutObjectRequest;
 
 import javax.crypto.KeyGenerator;
 import javax.crypto.SecretKey;

utils/checkstyle.xml

@@ -0,0 +1,27 @@
+<?xml version="1.0"?>
+<!DOCTYPE module PUBLIC
+        "-//Checkstyle//DTD Checkstyle Configuration 1.3//EN"
+        "https://checkstyle.org/dtds/configuration_1_3.dtd">
+
+<module name="Checker">
+    <!--
+        If you set the basedir property below, then all reported file
+        names will be relative to the specified directory. See
+        https://checkstyle.org/config.html#Checker
+        <property name="basedir" value="${basedir}"/>
+    -->
+    <property name="severity" value="error"/>
+
+    <property name="fileExtensions" value="java, properties, xml"/>
+
+    <module name="TreeWalker">
+        <!-- Checks for imports                              -->
+        <!-- See https://checkstyle.org/config_imports.html -->
+        <module name="AvoidStarImport"/>
+        <module name="IllegalImport"/> <!-- defaults to sun.* packages -->
+        <module name="RedundantImport"/>
+        <module name="UnusedImports">
+            <property name="processJavadoc" value="false"/>
+        </module>
+    </module>
+</module>