Log warning when HTTP client timeout is too low (#428)

* added warning log when http timeout is less than ilp expiry

Signed-off-by: nkramer44 <noah.ph.kramer@gmail.com>

link-parent/link-ilp-over-http/src/main/java/org/interledger/link/http/IlpOverHttpLink.java

@@ -41,6 +41,8 @@
 
 import java.io.ByteArrayOutputStream;
 import java.io.IOException;
+import java.time.Duration;
+import java.time.Instant;
 import java.util.Objects;
 import java.util.Optional;
 import java.util.function.Supplier;
@@ -120,6 +122,12 @@ public IlpOverHttpLink(
   public InterledgerResponsePacket sendPacket(final InterledgerPreparePacket preparePacket) {
     Objects.requireNonNull(preparePacket);
 
+    if (preparePacket.getExpiresAt() != null &&
+          okHttpClient.readTimeoutMillis() <= Duration.between(Instant.now(), preparePacket.getExpiresAt()).toMillis()) {
+      logger.warn("OkHttpClient read timeout is shorter than the Prepare Packet's timeout.  " +
+        "This may result in an HTTP timeout while unexpired ILP packets are in flight.");
+    }
+
     final Request okHttpRequest;
     try {
       final ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();