### Question:
Column implements ProtoObject<ColumnProto>, GsonObject { @Override public String toJson() { return CatalogGsonHelper.toJson(this, Column.class); } Column(String name, TypeDesc type);  Column(String name, DataType dataType);  Column(String name, TajoDataTypes.Type type);  Column(String name, Type type);  Column(ColumnProto proto); boolean hasQualifier(); String getQualifiedName(); String getQualifier(); String getSimpleName(); TypeDesc getTypeDesc(); Type getType(); DataType getDataType(); @Override boolean equals(Object o); int hashCode(); @Override ColumnProto getProto(); String toString(); @Override String toJson();  }### Answer:
@Test public final void testToJson() { Column col = new Column(field1.getProto()); String json = col.toJson(); Column fromJson = CatalogGsonHelper.fromJson(json, Column.class); assertEquals(col, fromJson); }