test(server): fix the nullness NullAway 0.14.1 finds in three tests (#1823)

Co-authored-by: Felix T.J. Dietrich <felix.dietrich@financial-health-initiative.org>

Author: FelixTJDietrich

server/application/src/test/java/de/tum/cit/aet/hephaestus/core/runtime/NoPerRequestAccessLogTest.java

@@ -56,12 +56,7 @@ void webappNginxDisablesTheAccessLogForTheWholeServerBlock() throws Exception {
 
     @Test
     void maintenancePageNginxDisablesTheAccessLogForTheWholeServerBlock() throws Exception {
-        String conf = propertyIn(PROXY_COMPOSE, "configs.nginx-default-config.content");
-
-        assertThat(conf)
-                .as("docker/compose.proxy.yaml no longer inlines an nginx server config under that key")
-                .isNotNull();
-        assertThat(directivesAtServerLevel(conf))
+        assertThat(directivesAtServerLevel(maintenancePageConf()))
                 .as("the maintenance page answers on a catch-all Host rule whenever the webapp router is "
                         + "down, so the URL it would log is the deep link the contributor was reaching for")
                 .contains("access_log off");
@@ -75,9 +70,8 @@ void maintenancePageNginxDisablesTheAccessLogForTheWholeServerBlock() throws Exc
     @Test
     void noNginxLocationReEnablesTheAccessLog() throws Exception {
         List<String> reEnabling = new ArrayList<>();
-        for (String conf : List.of(
-                Files.readString(WEBAPP_NGINX_CONF, StandardCharsets.UTF_8),
-                propertyIn(PROXY_COMPOSE, "configs.nginx-default-config.content"))) {
+        for (String conf :
+                List.of(Files.readString(WEBAPP_NGINX_CONF, StandardCharsets.UTF_8), maintenancePageConf())) {
             conf.lines()
                     .map(NoPerRequestAccessLogTest::directive)
                     .filter(line -> line.startsWith("access_log") && !line.equals("access_log off"))
@@ -89,6 +83,20 @@ void noNginxLocationReEnablesTheAccessLog() throws Exception {
                 .isEmpty();
     }
 
+    /**
+     * The maintenance page's nginx config is inlined into the compose file rather than shipped as a
+     * file, so a key that stops resolving would silently narrow both tests that read it to the webapp
+     * config alone. Asserting here names that as the failure instead.
+     */
+    private static String maintenancePageConf() throws IOException {
+        String conf = propertyIn(PROXY_COMPOSE, "configs.nginx-default-config.content");
+
+        assertThat(conf)
+                .as("docker/compose.proxy.yaml no longer inlines an nginx server config under that key")
+                .isNotNull();
+        return conf;
+    }
+
     /**
      * Directives written directly inside the single {@code server { … }} block — brace depth 1, so a
      * {@code location} nested inside it does not count.

server/application/src/test/java/de/tum/cit/aet/hephaestus/integration/schema/ProductionSchemaContractIntegrationTest.java

@@ -115,7 +115,7 @@ static void configureDatabase(DynamicPropertyRegistry registry) {
 
     @Test
     void observationForeignKeysPreserveTenantAndProvenance() {
-        List<String> foreignKeys = jdbcTemplate.queryForList("""
+        List<@Nullable String> foreignKeys = jdbcTemplate.queryForList("""
             SELECT DISTINCT rc.constraint_name || ':' || parent.table_name || ':' || rc.delete_rule
             FROM information_schema.referential_constraints rc
             JOIN information_schema.key_column_usage child

server/application/src/test/java/de/tum/cit/aet/hephaestus/practices/curated/CuratedCatalogAdminControllerIntegrationTest.java

@@ -1003,7 +1003,7 @@ private long overrideRows() {
         return rows;
     }
 
-    private List<String> auditValues(String entityType, String entityId) {
+    private List<@Nullable String> auditValues(String entityType, String entityId) {
         return jdbcTemplate.queryForList("""
             SELECT new_value::text
             FROM config_audit_event