Bad test is produced when use concrete classes for implementing interface with generic

[Markoutte]

Description

When there're only one implementation of some interface with generic type fuzzing choose this implementation even it is not suitable for a method.

To Reproduce

1. Use only fuzzer
2. Generate test for method test.

public class Implementations {

 public interface A<T> {
 T getValue();
 }

 public static class AImpl implements A<String> {

 private final String value;

 public AImpl(String value) {
 this.value = value;
 }

 @Override
 public String getValue() {
 return value;
 }
 }

 public static int test(A<Integer> value) {
 if (value.getValue() < 0) {
 return 0;
 }
 return value.getValue();
 }
}

Expected behavior

The only one method with null is generated, because there're no other options to create this class by fuzzer.

Actual behavior

2 tests are generated: with null and other with AImpl:

 @Test
 @DisplayName("test: arg_0 = AImpl(String) -> throw ClassCastException")
 public void testTestThrowsCCE() {
 AImpl aImpl = new AImpl("-3E");
 
 /* This test fails because method [sanity.Implementations.test] produces [java.lang.ClassCastException: java.lang.String cannot be cast to java.lang.Integer]
 sanity.Implementations.test(Implementations.java:24) */
 Implementations.test(aImpl);
 }

This test cannot be compiled.

Additional context

The issue was introduced by 19fc16c