Fix Kotlin 1.7 compatibility

apollo-gradle-plugin/src/main/kotlin/com/apollographql/apollo/gradle/internal/AndroidTaskConfigurator.kt

@@ -65,7 +65,7 @@ object AndroidTaskConfigurator {
       // Tell the kotlin compiler to compile our files
       project.tasks.named("compile${variant.name.capitalize()}Kotlin").configure {
         it.dependsOn(codegenProvider)
-        (it as KotlinCompile).source(codegenProvider.get().outputDir.asFile.get())
+        (it as KotlinCompile).invokeSource(codegenProvider.get().outputDir.asFile.get())
       }
     } else {
       variant.registerJavaGeneratingTask(codegenProvider.get(), codegenProvider.get().outputDir.get().asFile)
@@ -79,9 +79,9 @@ object AndroidTaskConfigurator {
        */
       project.tasks.matching {
         it.name == "compile${variant.name.capitalize()}Kotlin"
-      }.configureEach{
+      }.configureEach {
         it.dependsOn(codegenProvider)
-        (it as KotlinCompile).source(codegenProvider.get().outputDir.get().asFile)
+        (it as KotlinCompile).invokeSource(codegenProvider.get().outputDir.get().asFile)
       }
     }
   }

apollo-gradle-plugin/src/main/kotlin/com/apollographql/apollo/gradle/internal/JvmTaskConfigurator.kt

@@ -61,7 +61,7 @@ object JvmTaskConfigurator {
       project.tasks.matching {
         it.name == "compileKotlin"
       }.configureEach {
-        (it as KotlinCompile).source(codegenProvider.get().outputDir.get().asFile)
+        (it as KotlinCompile).invokeSource(codegenProvider.get().outputDir.get().asFile)
       }
     }
     sourceDirectorySet.srcDir(codegenProvider.flatMap { it.outputDir })

apollo-gradle-plugin/src/main/kotlin/com/apollographql/apollo/gradle/internal/KotlinCompileCompat.kt

@@ -0,0 +1,14 @@
+package com.apollographql.apollo.gradle.internal
+
+import org.jetbrains.kotlin.gradle.tasks.KotlinCompile
+
+// The signature of this function changed in Kotlin 1.7, so we invoke it reflectively
+// to support both.
+// 1.6.x: `fun source(vararg sources: Any): SourceTask
+// 1.7.x: `fun source(vararg sources: Any)
+fun KotlinCompile.invokeSource(source: Any) {
+  SOURCE_FUNCTION.invoke(this, arrayOf(source))
+}
+
+private val SOURCE_FUNCTION = KotlinCompile::class.java
+    .getMethod("source", java.lang.reflect.Array.newInstance(Any::class.java, 0).javaClass)