The engine can not handle some JDK APIs，e.g., Date

[alexeyfridman]

Description

SAT-1557

UTBot does not generate any meaningful (branches not leading to NPE) tests for the following code:

/**
 @param dateDate date
 @return String
 */
public static String dateToStr(java.util.Date dateDate) {
    SimpleDateFormat formatter = new SimpleDateFormat("yyyy-MM-dd");
    return formatter.format(dateDate);
}

To Reproduce

Steps to reproduce the behaviour:

1. Open any project in IntelliJ Idea
2. Use the plugin to generate tests
3. Open the generated tests

Expected behaviour

A test suite with full coverage of the MUT

Actual behaviour

The only branch with NPE

The example is too long due to static initializers, so I've decided not to paste it here.

Environment

Java 1.8
Mocks: disabled
Time limit: 60s

Other options do not matter.

Additional context

Probably, it happens because of too complicated Formatting for the engine.

[denis-fokin]

May be we need to take into account only the value of the Date (the long value)