sync: update from connectors monorepo

Author: nativebpm-bot

README.md

@@ -27,6 +27,16 @@ Ideal for large JSON bodies, multipart uploads, generated archives, or continuou
 Data is transmitted as it’s produced — the server can start processing immediately,  
 without waiting for the full body to be buffered.
 
+```mermaid
+flowchart TB
+    subgraph P["io.Pipe()"]
+        PW["PipeWriter"] --> PR["PipeReader"]
+    end
+
+    W["Writer (goroutine)"] -->|"writes into"| P
+    P -->|"provides data to"| R["Reader"]
+```
+
 ## Why Streaming Matters
 
 Traditional HTTP clients buffer request bodies entirely before sending.  
@@ -43,6 +53,7 @@ For large or dynamically generated payloads, this leads to:
 - [Streaming multipart upload](examples/multipart_streaming_example)
 - [Without fluent API (for comparison)](examples/multipart_streaming_example/multipart_streaming_without_fluent_api)
 - [Logger middleware](examples/logger_slog_example)
+- [Gotenbergo Client: Built on httpstream for efficient multipart uploads](https://github.com/nativebpm/gotenberg)
 
 ## License
 

internal/httprequest/multipart.go

@@ -2,6 +2,7 @@ package httprequest
 
 import (
 	"context"
+	"fmt"
 	"io"
 	"mime/multipart"
 	"net/http"
@@ -55,6 +56,23 @@ func (r *Multipart) Timeout(duration time.Duration) *Multipart {
 func (r *Multipart) Send() (*http.Response, error) {
 	ctx := r.request.Context()
 
+	// Pre-validate files to ensure they are not empty
+	for i, field := range r.fields {
+		if field.contentType == applicationOctetStream {
+			// Read first byte to check if file has content
+			buf := make([]byte, 1)
+			n, err := field.file.Read(buf)
+			if err != nil && err != io.EOF {
+				return nil, fmt.Errorf("failed to read file %s: %w", field.value, err)
+			}
+			if n == 0 {
+				return nil, fmt.Errorf("empty file: %s", field.value)
+			}
+			// Wrap reader to return the read byte back to the stream
+			r.fields[i].file = io.MultiReader(strings.NewReader(string(buf[:n])), field.file)
+		}
+	}
+
 	pr, pw := io.Pipe()
 	mw := multipart.NewWriter(pw)
 	r.request.Body = pr
@@ -72,18 +90,21 @@ func (r *Multipart) Send() (*http.Response, error) {
 				return
 			default:
 			}
+
 			switch field.contentType {
 			case multipartFormData:
 				if err := mw.WriteField(field.key, field.value); err != nil {
 					pw.CloseWithError(err)
 					return
 				}
+
 			case applicationOctetStream:
 				part, err := mw.CreateFormFile(field.key, field.value)
 				if err != nil {
 					pw.CloseWithError(err)
 					return
 				}
+
 				if _, err := io.Copy(part, field.file); err != nil {
 					pw.CloseWithError(err)
 					return