The FloatingDecimal tests in jdk/jdk/internal/math/FloatingDecimal rely on two supporting classes that date back to the early days of the platform, aptly named OldFDBigIntForTest and OldFloatingDecimalForTest. Their code is complex and used only in one test class.

The test class exercises both conversions from floating-point to string, and from string to floating-point (parsing). Since some releases, the former conversions are fully covered by tests in jdk/jdk/internal/math/ToDecimal and can be removed from the scope of the test.

On the other hand, the parsing test code can now rely on an independent implementation found in BigDecimal.

These moves make the supporting Old*ForTest classes obsolete, and they can be removed as well.

The test jdk/jdk/internal/math/ToString.java, too, exercises a dozen floating-point to string conversions amply covered already, and can be removed as well.