8287134: HttpURLConnection chunked streaming mode doesn't enforce specified size

Reviewed-by: dfuchs, michaelm

Author: c-cleary

src/java.base/share/classes/java/net/HttpURLConnection.java

@@ -277,9 +277,11 @@ public void setFixedLengthStreamingMode(long contentLength) {
      * <p>
      * This method must be called before the URLConnection is connected.
      *
-     * @param   chunklen The number of bytes to write in each chunk.
-     *          If chunklen is less than or equal to zero, a default
-     *          value will be used.
+     * @param   chunklen The number of bytes to be written in each chunk,
+     *          including a chunk size header as a hexadecimal string
+     *          (minimum of 1 byte), two CRLF's (4 bytes) and a minimum
+     *          payload length of 1 byte. If chunklen is less than or equal
+     *          to 5, a higher default value will be used.
      *
      * @throws  IllegalStateException if URLConnection is already connected
      *          or if a different streaming mode is already enabled.