### Question:
ExampleUserDefinedFunctionHandler extends UserDefinedFunctionHandler { public Long get_default_value_if_null(Long value) { return value == null ? 0 : value; } ExampleUserDefinedFunctionHandler(); Integer multiply(Integer factor1, Integer factor2); String concatenate(List<String> list); String to_json(Map<String, Object> struct); Long get_default_value_if_null(Long value);  }### Answer:
@Test public void testGetDefaultValueIfNullMethod() throws Exception { Schema inputSchema = SchemaBuilder.newBuilder() .addField("input", Types.MinorType.BIGINT.getType()) .build(); Schema outputSchema = SchemaBuilder.newBuilder() .addField("output", Types.MinorType.BIGINT.getType()) .build(); Block inputRecords = allocator.createBlock(inputSchema); inputRecords.setRowCount(2); BigIntVector fieldVector = (BigIntVector) inputRecords.getFieldVector("input"); fieldVector.setSafe(0, 123l); fieldVector.setNull(1); UserDefinedFunctionResponse response = runAndAssertSerialization(inputRecords, outputSchema, "get_default_value_if_null"); Block outputRecords = response.getRecords(); assertEquals(2, outputRecords.getRowCount()); FieldReader fieldReader = outputRecords.getFieldReader("output"); ArrowValueProjector arrowValueProjector = ProjectorUtils.createArrowValueProjector(fieldReader); assertEquals(exampleUserDefinedFunctionHandler.get_default_value_if_null(123l), arrowValueProjector.project(0)); assertEquals(exampleUserDefinedFunctionHandler.get_default_value_if_null(null), arrowValueProjector.project(1)); }