refactor: ChangeTemplate discovery strategy: annotation + file

core/flamingock-core-api/src/main/java/io/flamingock/api/annotations/ChangeTemplate.java

@@ -26,20 +26,20 @@
  * Marks a class as a Flamingock change template and configures its execution mode.
  *
  * <p>All template classes must extend {@link AbstractChangeTemplate} and be annotated with
- * this annotation to specify whether they process single or multiple steps.
+ * this annotation to specify their unique identifier and whether they process single or multiple steps.
  *
- * <p><b>Simple templates</b> (default, {@code steppable = false}):
+ * <p><b>Simple templates</b> (default, {@code multiStep = false}):
  * <pre>
  * id: create-users-table
- * template: SqlTemplate
+ * template: sql  # Uses the template id
  * apply: "CREATE TABLE users (id INT PRIMARY KEY)"
  * rollback: "DROP TABLE users"
  * </pre>
  *
- * <p><b>Steppable templates</b> ({@code steppable = true}) process multiple operations:
+ * <p><b>Steppable templates</b> ({@code multiStep = true}) process multiple operations:
  * <pre>
  * id: setup-orders
- * template: MongoTemplate
+ * template: mongo  # Uses the template id
  * steps:
  *   - apply: { type: createCollection, collection: orders }
  *     rollback: { type: dropCollection, collection: orders }
@@ -59,6 +59,18 @@
 @Target(ElementType.TYPE)
 public @interface ChangeTemplate {
 
+    /**
+     * Unique identifier for the template. Used in YAML files to reference
+     * the template (e.g., {@code template: "sql"}).
+     *
+     * <p>This is a mandatory field - all templates must have a unique identifier.
+     * The id should be short, descriptive, and use lowercase with hyphens
+     * (e.g., "sql", "mongodb", "dynamodb").
+     *
+     * @return the unique template identifier
+     */
+    String id();
+
     /**
      * When {@code true}, the template expects a {@code steps} array in YAML.
      * When {@code false} (default), it expects {@code apply} and optional {@code rollback} at root.

core/flamingock-core-api/src/test/java/io/flamingock/api/template/AbstractChangeTemplateReflectiveClassesTest.java

@@ -52,7 +52,7 @@ public static class AnotherAdditionalClass {
     }
 
     // Test template with custom generic types
-    @ChangeTemplate
+    @ChangeTemplate(id = "test-custom-types")
     public static class TestTemplateWithCustomTypes
             extends AbstractChangeTemplate<TestConfig, TestApplyPayload, TestRollbackPayload> {
 
@@ -67,7 +67,7 @@ public void apply() {
     }
 
     // Test template with additional reflective classes
-    @ChangeTemplate
+    @ChangeTemplate(id = "test-additional-classes")
     public static class TestTemplateWithAdditionalClasses
             extends AbstractChangeTemplate<TestConfig, TestApplyPayload, TestRollbackPayload> {
 
@@ -82,7 +82,7 @@ public void apply() {
     }
 
     // Test template with Void configuration
-    @ChangeTemplate
+    @ChangeTemplate(id = "test-void-config")
     public static class TestTemplateWithVoidConfig
             extends AbstractChangeTemplate<Void, String, String> {
 

core/flamingock-core-commons/src/main/java/io/flamingock/internal/common/core/metadata/FlamingockMetadata.java

@@ -16,7 +16,9 @@
 package io.flamingock.internal.common.core.metadata;
 
 import io.flamingock.internal.common.core.preview.PreviewPipeline;
+import io.flamingock.internal.common.core.template.TemplateMetadata;
 
+import java.util.List;
 import java.util.Map;
 
 public class FlamingockMetadata {
@@ -25,6 +27,7 @@ public class FlamingockMetadata {
     private String configFile;
     private Map<String, String> properties;
     private BuilderProviderInfo builderProvider;
+    private List<TemplateMetadata> templates;
 
     public FlamingockMetadata() {
     }
@@ -75,11 +78,20 @@ public boolean hasValidBuilderProvider() {
         return builderProvider != null && builderProvider.isValid();
     }
 
+    public List<TemplateMetadata> getTemplates() {
+        return templates;
+    }
+
+    public void setTemplates(List<TemplateMetadata> templates) {
+        this.templates = templates;
+    }
+
     @Override
     public String toString() {
         return "FlamingockMetadata{" + "pipeline=" + pipeline +
                 ", configFile='" + configFile + '\'' +
                 ", builderProvider=" + builderProvider +
+                ", templates=" + templates +
                 '}';
     }
 }