HttpRequest request = HttpRequest.builder().method("GET").endpoint("http://momma").build();
BindUserMetadataToHeadersWithPrefix binder = new BindUserMetadataToHeadersWithPrefix(
new BindMapToHeadersWithPrefix("prefix:"));
Blob blob = ContextBuilder.newBuilder("transient").buildInjector().getInstance(Blob.Factory.class).create(null);
blob.getMetadata().setUserMetadata(ImmutableMap.of("imageName", "foo", "serverId", "2"));
assertEquals(
binder.bindToRequest(request, blob),
HttpRequest.builder().method("GET").endpoint("http://momma")
.addHeader("prefix:imagename", "foo")