NullPointerException in TransactionExceptionHandler

[cmaan]

Starting with google-cloud-datastore:1.2.1, a user exception thrown within a datastore transaction (runInTransaction) triggers a NullPointerException in com.google.cloud.datastore.TransactionExceptionHandler. The original exception is swallowed.

For reference, a minimal build.gradle which triggers the problem on gradle run is:

import com.google.cloud.datastore.DatastoreOptions;

buildscript {
	repositories {
                mavenCentral()
                maven {
                       	url "https://jitpack.io"
                }
        }
	dependencies {
                //classpath "com.google.cloud:google-cloud-datastore:1.2.0" // works
                classpath "com.google.cloud:google-cloud-datastore:1.2.1" // breaks
                //classpath "com.google.cloud:google-cloud-datastore:1.2.2" // breaks
                //classpath "com.github.GoogleCloudPlatform.google-cloud-java:google-cloud-datastore:95f0dd7eb3b7b360ce51b1930c1f75cc2bb91140" // breaks
        }
}

task run() {
	def ds = DatastoreOptions.newBuilder()
                .build()
                .getService();
        ds.runInTransaction({ rw ->
                throw new RuntimeException("foobar");
        });
}

[neozwu]

fixed in #2256