Client with Java 8 runtime and Apache HttpClient 5 Transport fails wi…

…th java.lang.NoSuchMethodError: java.nio.ByteBuffer.flip()Ljava/nio/ByteBuffer

Signed-off-by: Andriy Redko <andriy.redko@aiven.io>

java-client/src/main/java/org/opensearch/client/transport/httpclient5/internal/HttpEntityAsyncEntityProducer.java

@@ -9,6 +9,7 @@
 package org.opensearch.client.transport.httpclient5.internal;
 
 import java.io.IOException;
+import java.nio.Buffer;
 import java.nio.ByteBuffer;
 import java.nio.channels.Channels;
 import java.nio.channels.ReadableByteChannel;
@@ -140,7 +141,7 @@ public void produce(final DataStreamChannel channel) throws IOException {
             }
         }
         if (byteBuffer.position() > 0) {
-            byteBuffer.flip();
+            ((Buffer)byteBuffer).flip();
             channel.write(byteBuffer);
             byteBuffer.compact();
         }