Update some comments to point at current RFCs (square#3561)

square#930

Author: swankjesse

okhttp/src/main/java/okhttp3/CacheControl.java

@@ -8,8 +8,7 @@
  * A Cache-Control header with cache directives from a server or client. These directives set policy
  * on what responses can be stored, and which requests can be satisfied by those stored responses.
  *
- * <p>See <a href="http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.9">RFC 2616,
- * 14.9</a>.
+ * <p>See <a href="https://tools.ietf.org/html/rfc7234#section-5.2">RFC 7234, 5.2</a>.
  */
 public final class CacheControl {
   /**

okhttp/src/main/java/okhttp3/Protocol.java

@@ -35,8 +35,8 @@ public enum Protocol {
   /**
    * A plaintext framing that includes persistent connections.
    *
-   * <p>This version of OkHttp implements <a href="http://github.com/%3Cspan%20class="x x-first x-last">http://www.ietf.org/rfc/rfc2616.txt">RFC
-   * 2616</a>, and tracks revisions to that spec.
+   * <p>This version of OkHttp implements <a href="http://github.com/%3Cspan%20class="x x-first x-last">https://tools.ietf.org/html/rfc7230">RFC
+   * 7230</a>, and tracks revisions to that spec.
    */
   HTTP_1_1("http/1.1"),
 

okhttp/src/main/java/okhttp3/internal/cache/CacheInterceptor.java

@@ -212,7 +212,7 @@ private Response cacheWritingResponse(final CacheRequest cacheRequest, Response
         .build();
   }
 
-  /** Combines cached headers with a network headers as defined by RFC 2616, 13.5.3. */
+  /** Combines cached headers with a network headers as defined by RFC 7234, 4.3.4. */
   private static Headers combine(Headers cachedHeaders, Headers networkHeaders) {
     Headers.Builder result = new Headers.Builder();
 

okhttp/src/main/java/okhttp3/internal/cache/CacheStrategy.java

@@ -295,7 +295,7 @@ private long computeFreshnessLifetime() {
 
     /**
      * Returns the current age of the response, in milliseconds. The calculation is specified by RFC
-     * 2616, 13.2.3 Age Calculations.
+     * 7234, 4.2.3 Calculating Age.
      */
     private long cacheResponseAge() {
       long apparentReceivedAge = servedDate != null

okhttp/src/main/java/okhttp3/internal/http/HttpDate.java

@@ -37,7 +37,7 @@ public final class HttpDate {
   private static final ThreadLocal<DateFormat> STANDARD_DATE_FORMAT =
       new ThreadLocal<DateFormat>() {
         @Override protected DateFormat initialValue() {
-          // RFC 2616 specified: RFC 822, updated by RFC 1123 format with fixed GMT.
+          // Date format specified by RFC 7231 section 7.1.1.1.
           DateFormat rfc1123 = new SimpleDateFormat("EEE, dd MMM yyyy HH:mm:ss 'GMT'", Locale.US);
           rfc1123.setLenient(false);
           rfc1123.setTimeZone(UTC);
@@ -90,7 +90,7 @@ public static Date parse(String value) {
         if (format == null) {
           format = new SimpleDateFormat(BROWSER_COMPATIBLE_DATE_FORMAT_STRINGS[i], Locale.US);
           // Set the timezone to use when interpreting formats that don't have a timezone. GMT is
-          // specified by RFC 2616.
+          // specified by RFC 7231.
           format.setTimeZone(UTC);
           BROWSER_COMPATIBLE_DATE_FORMATS[i] = format;
         }