public SqlSchemaBuilder addField(String name, SqlFieldSchema fieldType) {
    if (name == null || name.isEmpty() || fieldType == null)
      throw new IllegalArgumentException();

    fieldNames.add(name);
    fieldSchemas.add(fieldType);
    return this;
  }
Builder class to build the {@link SqlSchema}.
samza-api/src/main/java/org/apache/samza/sql/schema/SqlSchemaBuilder.java