Fixes googleapis#3739. Null check added to JobInfo fromPb(Job jobPb) and toPb() methods

Author: sombra-mykola-bakay

google-cloud-clients/google-cloud-bigquery/src/main/java/com/google/cloud/bigquery/JobInfo.java

@@ -180,7 +180,9 @@ static final class BuilderImpl extends Builder {
         this.statistics = JobStatistics.fromPb(jobPb);
       }
       this.userEmail = jobPb.getUserEmail();
-      this.configuration = JobConfiguration.fromPb(jobPb.getConfiguration());
+      if (jobPb.getConfiguration() != null) {
+        this.configuration = JobConfiguration.fromPb(jobPb.getConfiguration());
+      }
     }
 
     @Override
@@ -375,7 +377,9 @@ Job toPb() {
     if (statistics != null) {
       jobPb.setStatistics(statistics.toPb());
     }
-    jobPb.setConfiguration(configuration.toPb());
+    if(configuration != null){
+      jobPb.setConfiguration(configuration.toPb());
+    }
     return jobPb;
   }
 

google-cloud-clients/google-cloud-bigquery/src/test/java/com/google/cloud/bigquery/JobTest.java

@@ -523,6 +523,16 @@ public void testToAndFromPb() {
     compareJob(expectedJob, Job.fromPb(serviceMockReturnsOptions, expectedJob.toPb()));
   }
 
+  @Test
+  public void testToAndFromPbWithoutConfiguration() {
+    JobInfo jobInfo =
+        JobInfo.newBuilder(null)
+            .build();
+    initializeExpectedJob(4, jobInfo);
+    replay(bigquery);
+    compareJob(expectedJob, Job.fromPb(serviceMockReturnsOptions, expectedJob.toPb()));
+  }
+
   private void compareJob(Job expected, Job value) {
     assertEquals(expected, value);
     compareJobInfo(expected, value);