Load providers registered through the ServiceLoader mechanism.

Change-Id: I392e78b34c8330e9b4c06d57b1423ca552ba6fc1
diff --git a/example/src/main/resources/META-INF/services/eu.mulk.quarkus.googlecloud.jsonlogging.StructuredParameterProvider b/example/src/main/resources/META-INF/services/eu.mulk.quarkus.googlecloud.jsonlogging.StructuredParameterProvider
new file mode 100644
index 0000000..c0017e6
--- /dev/null
+++ b/example/src/main/resources/META-INF/services/eu.mulk.quarkus.googlecloud.jsonlogging.StructuredParameterProvider
@@ -0,0 +1 @@
+eu.mulk.quarkus.googlecloud.jsonlogging.example.RandomNumberParameterProvider