parquet-column/src/main/java/org/apache/parquet/schema/Types.java
public static PrimitiveBuilder<PrimitiveType> optional(PrimitiveTypeName type) {
    return new PrimitiveBuilder<PrimitiveType>(PrimitiveType.class, type)
        .repetition(Type.Repetition.OPTIONAL);
  }
public static PrimitiveBuilder<PrimitiveType> optional(PrimitiveTypeName type) {
    return new PrimitiveBuilder<PrimitiveType>(PrimitiveType.class, type)
        .repetition(Type.Repetition.OPTIONAL);
  }
Returns a builder to construct an optional {@link PrimitiveType}.

@param type a {@link PrimitiveTypeName} for the constructed type
@return a {@link PrimitiveBuilder}