FormatterFunc no longer extends Function or BiFunction. (#638)

Author: nedtwigg

CHANGES.md

@@ -21,6 +21,7 @@ We adhere to the [keepachangelog](https://keepachangelog.com/en/1.0.0/) format (
 * **BREAKING** `FileSignature` can no longer sign folders, only files.  Signatures are now based only on filename (not path), size, and a content hash.  It throws an error if a signature is attempted on a folder or on multiple files with different paths but the same filename - it never breaks silently.  This change does not break any of Spotless' internal logic, so it is unlikely to affect any of Spotless' consumers either. ([#571](https://github.com/diffplug/spotless/pull/571))
   * This change allows the maven plugin to cache classloaders across subprojects when loading config resources from the classpath (fixes [#559](https://github.com/diffplug/spotless/issues/559)).
   * This change also allows the gradle plugin to work with the remote buildcache (fixes [#280](https://github.com/diffplug/spotless/issues/280)).
+* **BREAKING** `FormatterFunc` no longer `extends ThrowingEx.Function` and `BiFunction`. In a major win for Java's idea of ["target typing"](https://cr.openjdk.java.net/~briangoetz/lambda/lambda-state-final.html), this required no changes anywhere in the codebase except deleting the `extends` part of `FormatterFunc` ([#638](https://github.com/diffplug/spotless/issues/638)).
 * **BREAKING** Heavy refactor of the `LicenseHeaderStep` public API.  Doesn't change internal behavior, but makes implementation of the gradle and maven plugins much easier. ([#628](https://github.com/diffplug/spotless/pull/628))
 * **BREAKING** Removed all deprecated methods and classes from `lib` and `lib-extra`.
   * [#629](https://github.com/diffplug/spotless/pull/629) removes the code which wasn't being used in plugin-gradle or plugin-maven.

lib/src/main/java/com/diffplug/spotless/FormatterFunc.java

@@ -24,8 +24,7 @@
  * to formatters.  If you need the File, see {@link NeedsFile}.
  */
 @FunctionalInterface
-public interface FormatterFunc
-		extends ThrowingEx.Function<String, String>, ThrowingEx.BiFunction<String, File, String> {
+public interface FormatterFunc {
 
 	String apply(String input) throws Exception;