HADOOP-16332. Remove S3A dependency on http core.

Contributed by Steve Loughran.

Change-Id: I53209c993a405fefdb5e1b692d5a56d027d3b845

hadoop-tools/hadoop-aws/pom.xml

@@ -406,11 +406,6 @@
       <artifactId>hadoop-common</artifactId>
       <scope>provided</scope>
     </dependency>
-    <dependency>
-      <groupId>org.apache.httpcomponents</groupId>
-      <artifactId>httpcore</artifactId>
-      <scope>provided</scope>
-    </dependency>
     <dependency>
       <groupId>org.apache.hadoop</groupId>
       <artifactId>hadoop-common</artifactId>

hadoop-tools/hadoop-aws/src/main/java/org/apache/hadoop/fs/s3a/impl/ChangeTracker.java

@@ -41,7 +41,6 @@ import org.apache.hadoop.fs.s3a.RemoteFileChangedException;
 import org.apache.hadoop.fs.s3a.S3ObjectAttributes;
 
 import static com.google.common.base.Preconditions.checkNotNull;
-import static org.apache.http.HttpStatus.SC_PRECONDITION_FAILED;
 
 /**
  * Change tracking for input streams: the version ID or etag of the object is
@@ -57,6 +56,8 @@ public class ChangeTracker {
   private static final Logger LOG =
       LoggerFactory.getLogger(ChangeTracker.class);
 
+  /** {@code 412 Precondition Failed} (HTTP/1.1 - RFC 2616) */
+  public static final int SC_PRECONDITION_FAILED = 412;
   public static final String CHANGE_REPORTED_BY_S3 = "Change reported by S3";
 
   /** Policy to use. */

hadoop-tools/hadoop-aws/src/test/java/org/apache/hadoop/fs/s3a/TestStreamChangeTracker.java

@@ -36,7 +36,6 @@ import org.apache.hadoop.fs.PathIOException;
 import org.apache.hadoop.fs.s3a.impl.ChangeDetectionPolicy;
 import org.apache.hadoop.fs.s3a.impl.ChangeTracker;
 import org.apache.hadoop.test.HadoopTestBase;
-import org.apache.http.HttpStatus;
 
 import static org.apache.hadoop.fs.s3a.impl.ChangeDetectionPolicy.CHANGE_DETECTED;
 import static org.apache.hadoop.fs.s3a.impl.ChangeDetectionPolicy.createPolicy;
@@ -250,7 +249,7 @@ public class TestStreamChangeTracker extends HadoopTestBase {
     // https://github.com/aws/aws-sdk-java/issues/1644
     AmazonServiceException awsException =
         new AmazonServiceException("aws exception");
-    awsException.setStatusCode(HttpStatus.SC_PRECONDITION_FAILED);
+    awsException.setStatusCode(ChangeTracker.SC_PRECONDITION_FAILED);
     expectChangeException(tracker, awsException, "copy",
         RemoteFileChangedException.PRECONDITIONS_FAILED);