diff --git a/celesta-core/src/main/java/ru/curs/celesta/dbutils/CursorGetHelper.java b/celesta-core/src/main/java/ru/curs/celesta/dbutils/CursorGetHelper.java
index 5e9649892f..9e268bf4af 100644
--- a/celesta-core/src/main/java/ru/curs/celesta/dbutils/CursorGetHelper.java
+++ b/celesta-core/src/main/java/ru/curs/celesta/dbutils/CursorGetHelper.java
@@ -16,6 +16,8 @@
 import java.util.Set;
 
 /**
+ * Helper class for retrieval of cursor data by key fields.
+ *
  * @author ioann
  * @since 2017-07-06
  */
diff --git a/celesta-core/src/main/java/ru/curs/celesta/dbutils/DbUpdater.java b/celesta-core/src/main/java/ru/curs/celesta/dbutils/DbUpdater.java
index 2ec99cac4e..4a2c91d1f0 100644
--- a/celesta-core/src/main/java/ru/curs/celesta/dbutils/DbUpdater.java
+++ b/celesta-core/src/main/java/ru/curs/celesta/dbutils/DbUpdater.java
@@ -115,7 +115,7 @@ public void updateDb() {
             Map<String, GrainInfo> dbGrains = new HashMap<>();
             while (schemaCursor.nextInSet()) {
 
-                if (!(EXPECTED_STATUSES.contains(schemaCursor.getState()))) {
+                if (!EXPECTED_STATUSES.contains(schemaCursor.getState())) {
                     throw new CelestaException("Cannot proceed with database upgrade: there are %s "
                             + "not in 'ready', 'recover' or 'lock' state.", getSchemasTableName());
                 }
diff --git a/celesta-core/src/main/java/ru/curs/celesta/dbutils/QueryBuildingHelper.java b/celesta-core/src/main/java/ru/curs/celesta/dbutils/QueryBuildingHelper.java
index ccc93640d2..f04dd63673 100644
--- a/celesta-core/src/main/java/ru/curs/celesta/dbutils/QueryBuildingHelper.java
+++ b/celesta-core/src/main/java/ru/curs/celesta/dbutils/QueryBuildingHelper.java
@@ -21,7 +21,7 @@ public interface QueryBuildingHelper {
     String translateDate(String date);
 
     /**
-     * Does RDBMS sort nulls first?
+     * Tells whether RDBMS sorts nulls first.
      */
     boolean nullsFirst();
 
diff --git a/celesta-core/src/main/java/ru/curs/celesta/dbutils/filter/Range.java b/celesta-core/src/main/java/ru/curs/celesta/dbutils/filter/Range.java
index 5c16374814..1dbaf7a732 100644
--- a/celesta-core/src/main/java/ru/curs/celesta/dbutils/filter/Range.java
+++ b/celesta-core/src/main/java/ru/curs/celesta/dbutils/filter/Range.java
@@ -53,8 +53,8 @@ public boolean filterEquals(AbstractFilter f) {
         if (f instanceof Range) {
             Object f2 = ((Range) f).valueFrom;
             Object t2 = ((Range) f).valueTo;
-            return (Objects.equals(valueFrom, f2))
-                    && (Objects.equals(valueTo, t2));
+            return Objects.equals(valueFrom, f2)
+                    && Objects.equals(valueTo, t2);
         } else {
             return false;
         }
diff --git a/celesta-core/src/main/java/ru/curs/celesta/dbutils/term/FromTerm.java b/celesta-core/src/main/java/ru/curs/celesta/dbutils/term/FromTerm.java
index 73b62e9937..766b74cd86 100644
--- a/celesta-core/src/main/java/ru/curs/celesta/dbutils/term/FromTerm.java
+++ b/celesta-core/src/main/java/ru/curs/celesta/dbutils/term/FromTerm.java
@@ -6,6 +6,8 @@
 import java.util.List;
 
 /**
+ * Values of the FROM clause of a SQL query.
+ *
  * @author ioann
  * @since 2017-08-16
  */
diff --git a/checkstyle.xml b/checkstyle.xml
index abdb285156..0a83e27d2f 100644
--- a/checkstyle.xml
+++ b/checkstyle.xml
@@ -66,7 +66,7 @@
         <module name="JavadocVariable">
             <property name="accessModifiers" value="public"/>
         </module>
-        <module name="JavadocStyle"/>
+        <module name="SummaryJavadoc"/>
 
         <!-- Checks for Naming Conventions.                  -->
         <!-- See http://checkstyle.sf.net/config_naming.html -->
diff --git a/pom.xml b/pom.xml
index 0cc2115def..6ba6031ab6 100644
--- a/pom.xml
+++ b/pom.xml
@@ -57,7 +57,7 @@
         <maven.compiler.release>17</maven.compiler.release>
 
         <!--dependency versions -->
-        <checkstyle.version>13.8.0</checkstyle.version>
+        <checkstyle.version>13.9.0</checkstyle.version>
         <slf4j.version>2.0.18</slf4j.version>
         <h2.version>2.4.240</h2.version>
         <javacc.version>7.0.13</javacc.version>