fix NPE

Author: PhongChuong

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

@@ -228,9 +228,11 @@ private Builder(com.google.api.services.bigquery.model.JobConfiguration configur
             CsvOptions.newBuilder()
                 .setEncoding(loadConfigurationPb.getEncoding())
                 .setFieldDelimiter(loadConfigurationPb.getFieldDelimiter())
-                .setPreserveAsciiControlCharacters(
-                    loadConfigurationPb.getPreserveAsciiControlCharacters())
                 .setQuote(loadConfigurationPb.getQuote());
+        if (loadConfigurationPb.getPreserveAsciiControlCharacters() != null) {
+          builder.setPreserveAsciiControlCharacters(
+              loadConfigurationPb.getPreserveAsciiControlCharacters());
+        }
         if (loadConfigurationPb.getAllowJaggedRows() != null) {
           builder.setAllowJaggedRows(loadConfigurationPb.getAllowJaggedRows());
         }