Make SymbolProcessorProvider a fun interface
diff --git a/api/src/main/kotlin/com/google/devtools/ksp/processing/SymbolProcessorProvider.kt b/api/src/main/kotlin/com/google/devtools/ksp/processing/SymbolProcessorProvider.kt
index 0e2ede2..ca2e82f 100644
--- a/api/src/main/kotlin/com/google/devtools/ksp/processing/SymbolProcessorProvider.kt
+++ b/api/src/main/kotlin/com/google/devtools/ksp/processing/SymbolProcessorProvider.kt
@@ -3,7 +3,7 @@
 /**
  * [SymbolProcessorProvider] is the interface used by plugins to integrate into Kotlin Symbol Processing.
  */
-interface SymbolProcessorProvider {
+fun interface SymbolProcessorProvider {
     /**
     * Called by Kotlin Symbol Processing to create the processor.
     *