Address review: document registration-only 4.3.1.2 bean and assert its schema SQL runs

application/src/main/java/org/thingsboard/server/service/install/lts/V4_3_1_2Migration.java

@@ -18,6 +18,17 @@ package org.thingsboard.server.service.install.lts;
 import org.springframework.stereotype.Component;
 import org.thingsboard.server.queue.util.TbCoreComponent;
 
+/**
+ * Registration-only migration with no {@link #apply()} (no data migration), kept intentionally.
+ * <p>
+ * {@link LtsMigrationService} selects migrations from the injected {@link LtsMigration} beans, not from the
+ * on-disk {@code data/upgrade/lts/<version>/} directories. So this bean is what makes the runner discover
+ * version {@code 4.3.1.2} and execute its {@code data/upgrade/lts/4.3.1.2/schema_update.sql} (which adds
+ * {@code calculated_field.additional_info}). A directory holding a {@code schema_update.sql} but lacking a
+ * matching bean would be silently skipped.
+ * <p>
+ * The dir/bean consistency (both ways) is guarded by a test in {@code LtsMigrationIntegrationTest}.
+ */
 @Component
 @TbCoreComponent
 public class V4_3_1_2Migration implements LtsMigration {

application/src/test/java/org/thingsboard/server/service/install/lts/LtsMigrationIntegrationTest.java

@@ -45,6 +45,7 @@ import java.util.stream.Collectors;
 import java.util.stream.Stream;
 
 import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertNotNull;
 import static org.junit.Assert.assertNull;
 import static org.junit.Assert.assertTrue;
@@ -174,6 +175,20 @@ public class LtsMigrationIntegrationTest extends AbstractControllerTest {
                 jdbcTemplate.queryForObject("SELECT schema_version FROM tb_schema_settings", Long.class));
     }
 
+    @Test
+    public void appliesSchemaForV4312AddsCalculatedFieldAdditionalInfo() {
+        // The test-context schema already ships calculated_field.additional_info, so drop it first to prove the
+        // 4.3.1.2 schema_update.sql (ALTER TABLE calculated_field ADD COLUMN IF NOT EXISTS additional_info) re-adds it.
+        jdbcTemplate.execute("ALTER TABLE calculated_field DROP COLUMN IF EXISTS additional_info");
+        assertFalse(columnExists("calculated_field", "additional_info"));
+
+        // Drive the runner over a range whose target (4.3.1.2) selects only the 4.3.1.2 migration.
+        ltsMigrationService.applyMigrations("4.3.1.1", "4.3.1.2");
+
+        // The 4.3.1.2 schema SQL ran: the column exists again.
+        assertTrue(columnExists("calculated_field", "additional_info"));
+    }
+
     @Test
     public void migrationDirectoriesAndBeansStayInSyncBothWays() {
         Path ltsDir = Paths.get(installScripts.getDataDir(), "upgrade", "lts");
@@ -216,4 +231,11 @@ public class LtsMigrationIntegrationTest extends AbstractControllerTest {
                 "SELECT EXISTS (SELECT 1 FROM information_schema.tables WHERE table_name = ?)", Boolean.class, table);
         return Boolean.TRUE.equals(exists);
     }
+
+    private boolean columnExists(String table, String column) {
+        Boolean exists = jdbcTemplate.queryForObject(
+                "SELECT EXISTS (SELECT 1 FROM information_schema.columns WHERE table_name = ? AND column_name = ?)",
+                Boolean.class, table, column);
+        return Boolean.TRUE.equals(exists);
+    }
 }