--- old/src/jdk.incubator.httpclient/share/classes/jdk/incubator/http/HttpHeaders.java	2017-11-30 04:03:59.598106418 -0800
+++ new/src/jdk.incubator.httpclient/share/classes/jdk/incubator/http/HttpHeaders.java	2017-11-30 04:03:59.287079228 -0800
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2015, 2016, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2015, 2017, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -29,55 +29,136 @@
 import java.util.Map;
 import java.util.Optional;
 import java.util.OptionalLong;
+import static java.util.Collections.emptyList;
+import static java.util.Collections.unmodifiableList;
+import static java.util.Objects.requireNonNull;
 
 /**
  * A read-only view of a set of HTTP headers.
  * {@Incubating}
  *
+ * <p> The methods of this class ( that accept a String header name ), and the
+ * Map returned by the {@linkplain #map() map} method, operate without regard to
+ * case when retrieving the header value.
+ *
+ * <p> HttpHeaders instances are immutable.
+ *
  * @since 9
  */
-public interface HttpHeaders {
+public abstract class HttpHeaders {
+
+    /**
+     * Creates an HttpHeaders.
+     */
+    protected HttpHeaders() {}
 
     /**
-     * Returns an {@link java.util.Optional} containing the first value of the
-     * given named (and possibly multi-valued) header. If the header is not
-     * present, then the returned {@code Optional} is empty.
+     * Returns an {@link Optional} containing the first value of the given named
+     * (and possibly multi-valued) header. If the header is not present, then
+     * the returned {@code Optional} is empty.
+     *
+     * @implSpec
+     * The default implementation invokes
+     * {@code allValues(name).stream().findFirst()}
      *
      * @param name the header name
      * @return an {@code Optional<String>} for the first named value
      */
-    public Optional<String> firstValue(String name);
+    public Optional<String> firstValue(String name) {
+        return allValues(name).stream().findFirst();
+    }
 
     /**
-     * Returns an {@link java.util.OptionalLong} containing the first value of the
-     * named header field. If the header is not
-     * present, then the Optional is empty. If the header is present but
-     * contains a value that does not parse as a {@code Long} value, then an
-     * exception is thrown.
+     * Returns an {@link OptionalLong} containing the first value of the
+     * named header field. If the header is not present, then the Optional is
+     * empty. If the header is present but contains a value that does not parse
+     * as a {@code Long} value, then an exception is thrown.
+     *
+     * @implSpec
+     * The default implementation invokes
+     * {@code allValues(name).stream().mapToLong(Long::valueOf).findFirst()}
      *
      * @param name the header name
      * @return  an {@code OptionalLong}
      * @throws NumberFormatException if a value is found, but does not parse as
      *                               a Long
      */
-    public OptionalLong firstValueAsLong(String name);
+    public OptionalLong firstValueAsLong(String name) {
+        return allValues(name).stream().mapToLong(Long::valueOf).findFirst();
+    }
 
     /**
      * Returns an unmodifiable List of all of the values of the given named
      * header. Always returns a List, which may be empty if the header is not
      * present.
      *
+     * @implSpec
+     * The default implementation invokes, among other things, the
+     * {@code map().get(name)} to retrieve the list of header values.
+     *
      * @param name the header name
      * @return a List of String values
      */
-    public List<String> allValues(String name);
+    public List<String> allValues(String name) {
+        requireNonNull(name);
+        List<String> values = map().get(name);
+        // Making unmodifiable list out of empty in order to make a list which
+        // throws UOE unconditionally
+        return values != null ? values : unmodifiableList(emptyList());
+    }
 
     /**
-     * Returns an unmodifiable multi Map view of this HttpHeaders. This
-     * interface should only be used when it is required to iterate over the
-     * entire set of headers.
+     * Returns an unmodifiable multi Map view of this HttpHeaders.
      *
      * @return the Map
      */
-    public Map<String,List<String>> map();
+    public abstract Map<String, List<String>> map();
+
+    /**
+     * Tests this HTTP headers instance for equality with the given object.
+     *
+     * <p> If the given object is not an {@code HttpHeaders} then this
+     * method returns {@code false}. Two HTTP headers are equal if each
+     * of their corresponding {@linkplain #map() maps} are equal.
+     *
+     * <p> This method satisfies the general contract of the {@link
+     * Object#equals(Object) Object.equals} method.
+     *
+     * @param obj the object to which this object is to be compared
+     * @return {@code true} if, and only if, the given object is an {@code
+     *         HttpHeaders} that is equal to this HTTP headers
+     */
+    public final boolean equals(Object obj) {
+        if (!(obj instanceof HttpHeaders))
+            return false;
+        HttpHeaders that = (HttpHeaders)obj;
+        return this.map().equals(that.map());
+    }
+
+    /**
+     * Computes a hash code for this HTTP headers instance.
+     *
+     * <p> The hash code is based upon the components of the HTTP headers
+     * {@linkplain #map() map}, and satisfies the general contract of the
+     * {@link Object#hashCode Object.hashCode} method.
+     *
+     * @return the hash-code value for this HTTP headers
+     */
+    public final int hashCode() {
+        return map().hashCode();
+    }
+
+    /**
+     * Returns this HTTP headers as a string.
+     *
+     * @return a string describing the HTTP headers
+     */
+    @Override
+    public String toString() {
+        StringBuilder sb = new StringBuilder();
+        sb.append(super.toString()).append(" ");
+        sb.append(map());
+        sb.append(" }");
+        return sb.toString();
+    }
 }