cleanup + documentation and add the current schema-dump

src/test/java/net/hostsharing/hsadminng/hs/migration/LiquibaseCompatibilityIntegrationTest.java

@@ -19,6 +19,9 @@ import javax.sql.DataSource;
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.springframework.test.context.jdbc.Sql.ExecutionPhase.BEFORE_TEST_CLASS;
 
+// TODO.impl: The reference-SQL-dump-generation needs to be automated
+// HOWTO: generate the prod-reference-SQL-dump during a prod-release
+
 /** Tests, if the Liquibase scripts can be applied to a database ionitialized with schemas
     and test-data from a previous version.
 
@@ -33,14 +36,24 @@ import static org.springframework.test.context.jdbc.Sql.ExecutionPhase.BEFORE_TE
 
         <li>create the reference-schema SQL-file with some initializations:</li>
             <pre><code>cat >src/test/resources/db/prod-only-office-schema-with-test-data.sql <<EOF
-            CREATE ROLE postgres;
+-- =================================================================================
+-- Generated reference-SQL-dump (hopefully of latest prod-release).
+-- See: net.hostsharing.hsadminng.hs.migration.LiquibaseCompatibilityIntegrationTest
+-- ---------------------------------------------------------------------------------
 
-            CREATE ROLE admin;
-            GRANT ALL PRIVILEGES ON ALL TABLES IN SCHEMA public TO admin;
-            CREATE ROLE restricted;
-            GRANT ALL PRIVILEGES ON ALL TABLES IN SCHEMA public TO restricted;
+--
+-- Explicit pre-initialization because we cannot use \`pg_dump --create ...\`
+-- because the database is already created by Testcontainers.
+--
 
-            EOF
+CREATE ROLE postgres;
+
+CREATE ROLE admin;
+GRANT ALL PRIVILEGES ON ALL TABLES IN SCHEMA public TO admin;
+CREATE ROLE restricted;
+GRANT ALL PRIVILEGES ON ALL TABLES IN SCHEMA public TO restricted;
+
+EOF
          </code></pre>
 
         <li>add the dump to that reference-schema SQL-file:</p>