Generated types don't give informative exceptions when required values not provided

[garrettjonesgoogle]

TopicName.newBuilder().build() will compile but will throw NPE, but you can't tell which field/attribute is missing.

Exception in thread "main" java.lang.NullPointerException
	at com.google.common.base.Preconditions.checkNotNull(Preconditions.java:212)
	at com.google.pubsub.v1.TopicName.<init>(TopicName.java:51)
	at com.google.pubsub.v1.TopicName.<init>(TopicName.java:26)
	at com.google.pubsub.v1.TopicName$Builder.build(TopicName.java:115)
	at com.google.cloud.camel.PubSubExample.main(PubSubExample.java:25)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at com.intellij.rt.execution.application.AppMain.main(AppMain.java:147)