private static List<TableFieldSchema> toTableFieldSchema(Schema schema) { List<TableFieldSchema> fields = new ArrayList<>(schema.getFieldCount()); for (Field schemaField : schema.getFields()) { FieldType type = schemaField.getType(); TableFieldSchema field = new TableFieldSchema().setName(schemaField.getName()); if (schemaField.getDescription() != null && !"".equals(schemaField.getDescription())) { field.setDescription(schemaField.getDescription()); } if (!schemaField.getNullable()) { field.setMode(Mode.REQUIRED.toString()); } if (TypeName.ARRAY == type.getTypeName()) { type = type.getCollectionElementType(); field.setMode(Mode.REPEATED.toString()); } if (TypeName.ROW == type.getTypeName()) { Schema subType = type.getRowSchema(); field.setFields(toTableFieldSchema(subType)); } field.setType(toStandardSQLTypeName(type).toString()); fields.add(field); } return fields; }