Fix incorrect Buffer#setBytes(ByteBuffer) length calculation

Author: shblue21

vertx-core/src/main/java/io/vertx/core/buffer/impl/BufferImpl.java

@@ -502,7 +502,7 @@ public BufferImpl setBuffer(int pos, Buffer buffer, int offset, int len) {
   }
 
   public BufferImpl setBytes(int pos, ByteBuffer b) {
-    ensureLength(pos + b.limit());
+    ensureLength(pos + b.remaining());
     buffer.setBytes(pos, b);
     return this;
   }

vertx-core/src/test/java/io/vertx/tests/buffer/BufferTest.java

@@ -915,6 +915,19 @@ public void testSetBytesBuffer2() throws Exception {
     assertNullPointerException(() -> Buffer.buffer(150).setBytes(0, (ByteBuffer) null));
   }
 
+  @Test
+  public void testSetBytesByteBufferUsesRemaining() {
+    ByteBuffer src = ByteBuffer.wrap(new byte[] { 10, 20, 30, 40, 50 });
+    src.position(2);
+
+    Buffer dst = Buffer.buffer();
+    dst.setBytes(1, src);
+
+    assertEquals(4, dst.length());
+    assertTrue(TestUtils.byteArraysEqual(new byte[] { 0, 30, 40, 50 }, dst.getBytes()));
+    assertEquals(src.limit(), src.position());
+  }
+
   private void testSetBytesBuffer(Buffer buff, Function<byte[], Buffer> bufferFactory) throws Exception {
     Buffer b = bufferFactory.apply(TestUtils.randomByteArray(100));
     buff.setBuffer(50, b);