chore: address pr feedback

Author: keshavdandeva

java-bigquery/google-cloud-bigquery/src/main/java/com/google/cloud/bigquery/BigQueryImpl.java

@@ -452,7 +452,7 @@ && getOptions().getOpenTelemetryTracer() != null) {
           getOptions()
               .getOpenTelemetryTracer()
               .spanBuilder("com.google.cloud.bigquery.BigQuery.createJob")
-              .setAllAttributes(jobInfo.getJobId() != null ? jobInfo.getJobId().getOtelAttributes() : null)
+              .setAllAttributes(jobInfo.getJobId() != null ? jobInfo.getJobId().getOtelAttributes() : Attributes.empty())
               .setAllAttributes(otelAttributesFromOptions(options))
               .startSpan();
     }
@@ -2072,7 +2072,7 @@ && getOptions().getOpenTelemetryTracer() != null) {
           getOptions()
               .getOpenTelemetryTracer()
               .spanBuilder("com.google.cloud.bigquery.BigQuery.queryWithTimeout")
-              .setAllAttributes(jobId != null ? jobId.getOtelAttributes() : null)
+              .setAllAttributes(jobId != null ? jobId.getOtelAttributes() : Attributes.empty())
               .setAllAttributes(otelAttributesFromOptions(options))
               .startSpan();
     }
@@ -2125,7 +2125,7 @@ && getOptions().getOpenTelemetryTracer() != null) {
           getOptions()
               .getOpenTelemetryTracer()
               .spanBuilder("com.google.cloud.bigquery.BigQuery.getQueryResults")
-              .setAllAttributes(jobId != null ? jobId.getOtelAttributes() : null)
+              .setAllAttributes(jobId != null ? jobId.getOtelAttributes() : Attributes.empty())
               .setAllAttributes(otelAttributesFromOptions(options))
               .startSpan();
     }