Closes #1539 kebab caseificiation (#1603)

* Strip any leading - but no other character when converting from case camel case to kebab case. Fixes 1539

CHANGELOG.md

@@ -10,6 +10,7 @@ Thank you!
 * Fixes a regression from 0.18.4 which incorrectly rendered default values for certain types (see [#1593](https://github.com/disneystreaming/smithy4s/pull/1593))
 * Fixes an issue in which union members targetting Unit would fail to compile when used as traits (see [#1600](https://github.com/disneystreaming/smithy4s/pull/1600)).
 * Make the `transform` method in generated `*Gen` algebras final. This should make it possible to derive e.g. `FunctorK` instances in cats-tagless automatically (see [#1588](https://github.com/disneystreaming/smithy4s/pull/1588)).
+* Fixes commons.toKebabCase() sometimes drops the first letter (see [#1603](https://github.com/disneystreaming/smithy4s/pull/1603)).
 
 # 0.18.24
 

modules/decline/src/core/commons.scala

@@ -28,7 +28,7 @@ import java.util.Base64
 
 object commons {
   def toKebabCase(s: String): String =
-    s.replaceAll("([A-Z])", "-$1").toLowerCase.drop(1)
+    s.replaceAll("([A-Z])", "-$1").toLowerCase.stripPrefix("-")
 
   implicit def covariantAnyFunctor[F[_]](implicit
       ev: MonadError[F, ConstraintError]

modules/decline/test/src/smithy4s/decline/core/CommonsSpec.scala

@@ -0,0 +1,18 @@
+package smithy4s.decline.core
+
+import weaver._
+
+object CommonsSpec extends FunSuite {
+
+  test("toKebabCase base case") {
+    expect(
+      commons.toKebabCase("StartsWithUpperCase") == "starts-with-upper-case"
+    )
+  }
+
+  test("toKebabCase starts with lower case") {
+    expect(
+      commons.toKebabCase("startsWithLowerCase") == "starts-with-lower-case"
+    )
+  }
+}