@java.lang.Override
    public void writeTo(com.google.protobuf.CodedOutputStream output) throws java.io.IOException {
      if (((bitField0_ & 0x00000001) != 0)) {
        output.writeMessage(1, getScheduleTime());
      }
      if (intervalDurationDays_ != 0) {
        output.writeInt32(2, intervalDurationDays_);
      }
      getUnknownFields().writeTo(output);
    }
<pre>
Required. The duration of time between executions in days.
</pre>

<code>int32 interval_duration_days = 2 [(.google.api.field_behavior) = REQUIRED];</code>

@return The intervalDurationDays.
java-websecurityscanner/proto-google-cloud-websecurityscanner-v1alpha/src/main/java/com/google/cloud/websecurityscanner/v1alpha/ScanConfig.java