Streamline default value management for KotlinFeatures.

release-notes/CREDITS-2.x

@@ -18,6 +18,7 @@ Contributors:
 # 2.16.0 (not yet released)
 
 WrongWrong (@k163377)
+* #685: Streamline default value management for KotlinFeatures
 * #684: Update Kotlin Version to 1.6
 * #682: Remove MissingKotlinParameterException and replace with MismatchedInputException
 

release-notes/VERSION-2.x

@@ -18,6 +18,8 @@ Co-maintainers:
 
 2.16.0 (not yet released)
 
+#685: Streamline default value management for KotlinFeatures.
+ This improves the initialization cost of kotlin-module a little.
 #684: Kotlin 1.5 has been deprecated and the minimum supported Kotlin version will be updated to 1.6.
 #682: Remove MissingKotlinParameterException and replace with MismatchedInputException
  This change removes MissingKotlinParameterException and resolves #617.

src/main/kotlin/com/fasterxml/jackson/module/kotlin/KotlinFeature.kt

@@ -44,12 +44,12 @@ enum class KotlinFeature(private val enabledByDefault: Boolean) {
      */
     StrictNullChecks(enabledByDefault = false);
 
-    internal val bitSet: BitSet = 2.0.pow(ordinal).toInt().toBitSet()
+    internal val bitSet: BitSet = (1 shl ordinal).toBitSet()
 
     companion object {
         internal val defaults
-            get() = 0.toBitSet().apply {
-                values().filter { it.enabledByDefault }.forEach { or(it.bitSet) }
+            get() = values().fold(BitSet(Int.SIZE_BITS)) { acc, cur ->
+                acc.apply { if (cur.enabledByDefault) this.or(cur.bitSet) }
             }
     }
 }