diff a/src/java.net.http/share/classes/java/net/http/HttpRequest.java b/src/java.net.http/share/classes/java/net/http/HttpRequest.java
--- a/src/java.net.http/share/classes/java/net/http/HttpRequest.java
+++ b/src/java.net.http/share/classes/java/net/http/HttpRequest.java
@@ -34,13 +34,16 @@
 import java.nio.file.Files;
 import java.nio.file.OpenOption;
 import java.nio.file.Path;
 import java.time.Duration;
 import java.util.Iterator;
+import java.util.List;
+import java.util.Map;
 import java.util.Objects;
 import java.util.Optional;
 import java.util.concurrent.Flow;
+import java.util.function.BiFunction;
 import java.util.function.Supplier;
 import jdk.internal.net.http.HttpRequestBuilderImpl;
 import jdk.internal.net.http.RequestPublishers;
 import static java.nio.charset.StandardCharsets.UTF_8;
 
@@ -652,7 +655,83 @@
          *         no request body.
          */
         public static BodyPublisher noBody() {
             return new RequestPublishers.EmptyPublisher();
         }
+
+        // -- Minimal piece of low-level machinery
+
+        /**
+         * A request body publisher which publishes items emitted by each of the
+         * given request body publishers, one after the other, without
+         * interleaving.
+         *
+         * // TODO: tighten spec, subscribe to each publisher in turn, drain,
+         * // to onComplete, next... Any error encountered is propagated and
+         * // no further activity, etc ...
+         * // The content-length of the returned publisher will be that of the
+         * // accumulated publisher lengths, unless any is unknown in which case
+         * // the returned publisher's content-length is unknown.
+         *
+         * @param publishers an array of request body publishers
+         * @return a BodyPublisher composed of the given publishers
+         * @throws IllegalArgumentException if publishers array is less than 2
+         */
+        public static BodyPublisher concat(BodyPublisher... publishers) {
+            Objects.requireNonNull(publishers);
+            if (publishers.length < 2)
+                throw new IllegalArgumentException("error");
+
+            return null; // TODO implement
+        }
+
+        // -- The following are three alternatives to support multipart common syntax
+
+        /**
+         * A multipart part!  Alternative #1 requires a carrier tuple (Uck!)
+         *
+         * @headers the, possibly empty, part's headers  << headers are optional
+         * @publisher the non-null part's publisher
+         */
+        public static record Part(HttpHeaders headers, BodyPublisher publisher) { }
+
+        /**
+         * A multipart request body publisher...
+         *
+         * Publishes each of the given parts, one after another, in order. Each
+         * part is separated by the given boundary.
+         *
+         * // TODO: tighten spec, content-length?, etc
+         *
+         * TODO: supports the multipart common syntax, see https://tools.ietf.org/html/rfc2046#section-5.1.1
+         *
+         * One can embed multipart inside multipart - verify
+         *
+         * @param boundary a non-null boundary
+         * @param parts an non-null array of multipart parts
+         * @throws IllegalArgumentException if boundary not less than 70 chars ...
+         *         if parts does not contain at least one element ...
+         * @return a multipart BodyPublisher
+         */
+        // Alternative #1
+        public static BodyPublisher ofMultipart(String boundary, Part... parts) {
+            return null; // TODO implement
+        }
+
+        // Alternative #2
+        public static BodyPublisher ofMultipart2(String boundary,
+                                                 List<Map.Entry<HttpHeaders,BodyPublisher>> parts) {
+            return null; // TODO implement
+        }
+
+        // Alternative #3
+        public static BodyPublisher ofMultipart3(String boundary,
+                                                 BodyPublisher... parts) {  // this is ambiguous(ish) OR maybe not, default ascii/text?
+            return null; // TODO implement
+        }
+
+        public static BodyPublisher multipartPart(HttpHeaders headers,  // what a name!
+                                                  BodyPublisher publisher) {
+            return concat(ofString(headers.toString()), publisher);  // Argh! header to string representation
+        }
     }
 }