Migrate TestNG SoftAssert to AssertJ SoftAssertions

[juherr]

What's changed

Adds a TestNgSoftAssertToAssertJ recipe, wired into the existing TestNgToAssertj declarative recipe, to migrate TestNG soft assertions (org.testng.asserts.SoftAssert) to AssertJ soft assertions (org.assertj.core.api.SoftAssertions).

// before
SoftAssert softAssert = new SoftAssert();
softAssert.assertEquals(actual, expected);   // TestNG: actual first, expected second
softAssert.assertTrue(cond, "msg");
softAssert.assertAll();

// after
SoftAssertions softAssert = new SoftAssertions();
softAssert.assertThat(actual).isEqualTo(expected);
softAssert.assertThat(cond).as("msg").isTrue();
softAssert.assertAll();

How it works

The instance assertion calls are rewritten first, keeping the receiver, then a ChangeType step handles the variable type, the constructor, imports, and the identically named assertAll()/fail(...) methods.

The assertion methods (assertEquals, assertTrue, ...) are declared on org.testng.asserts.Assertion — SoftAssert only adds assertAll — so the matcher targets Assertion and a receiver-type guard keeps direct Assertion (hard) usage untouched.

Covered methods

• assertEquals / assertNotEquals — preserving TestNG's (actual, expected) order, plus the message and floating-point delta overloads (isCloseTo(..., within(...)) / isNotCloseTo(...))
• assertTrue / assertFalse
• assertNull / assertNotNull
• assertSame / assertNotSame
• assertEqualsNoOrder → containsExactlyInAnyOrder
• assertAll() and fail(...) keep the same name and are handled by ChangeType

Notes

• Broadens the assertj-core onlyIfUsing dependency trigger from org.testng.* to org.testng..*, so classes using only org.testng.asserts.SoftAssert still get the dependency added.
• The lambda form SoftAssertions.assertSoftly(s -> { ... }) is intentionally not emitted; the explicit instance + assertAll() shape is a 1:1 mapping.

Tests added to TestNgToAssertJTest cover the full flow, every overload branch, non-variable receivers (inline new SoftAssert() and fields), the assertEqualsNoOrder mapping, fail(...) passthrough, boxed-Double deltas, and a negative test asserting direct Assertion usage is left unchanged.

[timtebeek]

Perfect, thanks a lot! Good to see this soft assert gap closed as well. We'll likely do a .patch release later today, or the regular release mid next week.