Generate version provider into module-specific package (#1219)

The GeneratedVersionProvider was being generated into the shared
versionspi package in every module, causing duplicate class conflicts.
Generate it into each module's own package instead so every JAR has
a unique FQCN.

Author: sugmanue

buildSrc/src/main/kotlin/GenerateVersionProviderTask.kt

@@ -6,6 +6,9 @@ import java.io.File
 
 /**
  * Gradle task that generates a SmithyVersionProvider SPI implementation for a module.
+ *
+ * The implementation is generated into the module's own package to avoid classpath
+ * conflicts when multiple modules are on the classpath.
  */
 abstract class GenerateVersionProviderTask : DefaultTask() {
 
@@ -19,7 +22,7 @@ abstract class GenerateVersionProviderTask : DefaultTask() {
     var outputDir: File = project.layout.buildDirectory.dir("generated/version-provider").get().asFile
 
     companion object {
-        private const val PACKAGE = "software.amazon.smithy.java.versionspi"
+        private const val SPI_PACKAGE = "software.amazon.smithy.java.versionspi"
         private const val INTERFACE_NAME = "SmithyVersionProvider"
         private const val RECORD_NAME = "ModuleVersion"
         private const val IMPL_NAME = "GeneratedVersionProvider"
@@ -32,13 +35,22 @@ abstract class GenerateVersionProviderTask : DefaultTask() {
         val minor = parts.getOrElse(1) { "0" }
         val patch = parts.getOrElse(2) { "0" }.replace(Regex("[^0-9].*"), "")
 
-        val packageDir = File(outputDir, "java/${PACKAGE.replace('.', '/')}")
+        // Use the module's own package for the implementation class
+        val implPackage = moduleName
+        val packageDir = File(outputDir, "java/${implPackage.replace('.', '/')}")
         packageDir.mkdirs()
 
-        // Generate the implementation
+        val fqInterface = "$SPI_PACKAGE.$INTERFACE_NAME"
+        val fqRecord = "$SPI_PACKAGE.$RECORD_NAME"
+        val fqImpl = "$implPackage.$IMPL_NAME"
+
+        // Generate the implementation in the module's own package
         File(packageDir, "$IMPL_NAME.java").writeText(
             """
-            |package $PACKAGE;
+            |package $implPackage;
+            |
+            |import $fqInterface;
+            |import $fqRecord;
             |
             |public final class $IMPL_NAME implements $INTERFACE_NAME {
             |    private static final $RECORD_NAME VERSION = new $RECORD_NAME("$moduleName", $major, $minor, $patch);
@@ -54,8 +66,8 @@ abstract class GenerateVersionProviderTask : DefaultTask() {
         // Generate META-INF/services file
         val servicesDir = File(outputDir, "resources/META-INF/services")
         servicesDir.mkdirs()
-        File(servicesDir, "$PACKAGE.$INTERFACE_NAME").writeText(
-            "$PACKAGE.$IMPL_NAME\n"
+        File(servicesDir, fqInterface).writeText(
+            "$fqImpl\n"
         )
     }
 }