Identify target fields and use assertEquals or assertNotEquals for them

[alisevych]

Description

We can identify the target fields of the Object, which states should be tested.
Then we can add assertions only for them.
That allows to avoid reflection for creating expected Objects.

Suggested behavior

For example:
There is a method call that transforms initial Object(s) - and changes only particular fields:

• we can add assertNotEquals(expectedValue, actualObject.fieldName) only for the changed fields.

Currently

Currently we get a test with assertEquals(expectedObject, actualObject), that compares actual and expected Objects totally.
expectedObject is often created using Reflection, setting fields that we do not need to test.

[alisevych]

Here is a related bug for Go language support:
One particular field in Structure should be not NaN. Others should not change.

• Go. Assertions for structures should be accurate #1809