Add missing separator between part custom header name and value, close AsyncHttpClient#1168

Author: slandelle

client/src/main/java/org/asynchttpclient/request/body/multipart/part/MultipartPart.java

@@ -76,6 +76,11 @@ public abstract class MultipartPart<T extends PartBase> implements Closeable {
      * Content type header as a byte array
      */
     private static final byte[] CONTENT_TRANSFER_ENCODING_BYTES = "Content-Transfer-Encoding: ".getBytes(US_ASCII);
+    
+    /**
+     * Content type header as a byte array
+     */
+    private static final byte[] HEADER_NAME_VALUE_SEPARATOR_BYTES = ": ".getBytes(US_ASCII);
 
     /**
      * Content type header as a byte array
@@ -303,6 +308,7 @@ protected void visitCustomHeaders(PartVisitor visitor) {
             for (Param param : part.getCustomHeaders()) {
                 visitor.withBytes(CRLF_BYTES);
                 visitor.withBytes(param.getName().getBytes(US_ASCII));
+                visitor.withBytes(HEADER_NAME_VALUE_SEPARATOR_BYTES);
                 visitor.withBytes(param.getValue().getBytes(US_ASCII));
             }
         }

client/src/test/java/org/asynchttpclient/request/body/multipart/part/MultipartPartTest.java

@@ -143,7 +143,7 @@ public void testVisitCustomHeaders() {
         try (TestMultipartPart multipartPart = new TestMultipartPart(fileLikePart, new byte[0])) {
             CounterPartVisitor counterVisitor = new CounterPartVisitor();
             multipartPart.visitCustomHeaders(counterVisitor);
-            assertEquals(counterVisitor.getCount(), 27, "CounterPartVisitor count for visitCustomHeaders should include the length of the custom headers");
+            assertEquals(counterVisitor.getCount(), 29, "CounterPartVisitor count for visitCustomHeaders should include the length of the custom headers");
         }
     }
 
@@ -164,7 +164,7 @@ public void testVisitPreContent() {
         try (TestMultipartPart multipartPart = new TestMultipartPart(fileLikePart, new byte[0])) {
             CounterPartVisitor counterVisitor = new CounterPartVisitor();
             multipartPart.visitPreContent(counterVisitor);
-            assertEquals(counterVisitor.getCount(), 214, "CounterPartVisitor count for visitPreContent should " + "be equal to the sum of the lengths of precontent");
+            assertEquals(counterVisitor.getCount(), 216, "CounterPartVisitor count for visitPreContent should " + "be equal to the sum of the lengths of precontent");
         }
     }
 
@@ -265,7 +265,5 @@ protected long transferContentTo(ByteBuf target) throws IOException {
         protected long transferContentTo(WritableByteChannel target) throws IOException {
             return 0;
         }
-
     }
-
 }