diff --git a/pom.xml b/pom.xml
index 37be673..cf4c78f 100644
--- a/pom.xml
+++ b/pom.xml
@@ -60,6 +60,12 @@ OF THE POSSIBILITY OF SUCH DAMAGE.
     </site>
   </distributionManagement>
   <dependencies>
+    <dependency>
+      <groupId>javax.validation</groupId>
+      <artifactId>validation-api</artifactId>
+      <version>2.0.1.Final</version>
+      <scope>provided</scope>
+    </dependency>
     <dependency>
       <groupId>org.projectlombok</groupId>
       <artifactId>lombok</artifactId>
@@ -227,6 +233,7 @@ OF THE POSSIBILITY OF SUCH DAMAGE.
             <configuration>
               <excludes combine.children="append">
                 <exclude>findbugs:.*</exclude>
+                <exclude>duplicatefinder:.*</exclude>
               </excludes>
             </configuration>
           </plugin>
diff --git a/src/main/java/com/jcabi/dynamo/AttributeUpdates.java b/src/main/java/com/jcabi/dynamo/AttributeUpdates.java
index 8b07d47..e564446 100644
--- a/src/main/java/com/jcabi/dynamo/AttributeUpdates.java
+++ b/src/main/java/com/jcabi/dynamo/AttributeUpdates.java
@@ -38,11 +38,9 @@
 import com.jcabi.immutable.ArrayMap;
 import java.util.ArrayList;
 import java.util.Collection;
-import java.util.Locale;
 import java.util.Map;
 import java.util.Set;
 import java.util.concurrent.ConcurrentHashMap;
-import java.util.concurrent.ConcurrentMap;
 import lombok.EqualsAndHashCode;
 
 /**
diff --git a/src/main/java/com/jcabi/dynamo/AwsItem.java b/src/main/java/com/jcabi/dynamo/AwsItem.java
index 2c3a3e1..05e676c 100644
--- a/src/main/java/com/jcabi/dynamo/AwsItem.java
+++ b/src/main/java/com/jcabi/dynamo/AwsItem.java
@@ -45,7 +45,6 @@
 import com.jcabi.log.Logger;
 import java.io.IOException;
 import java.util.Collections;
-import java.util.Locale;
 import java.util.Map;
 import java.util.NoSuchElementException;
 import lombok.EqualsAndHashCode;
@@ -60,6 +59,7 @@
 @Loggable(Loggable.DEBUG)
 @ToString
 @EqualsAndHashCode(of = { "credentials", "frm", "name", "attributes" })
+@SuppressWarnings("PMD.GuardLogStatement")
 final class AwsItem implements Item {
 
     /**
diff --git a/src/main/java/com/jcabi/dynamo/AwsIterator.java b/src/main/java/com/jcabi/dynamo/AwsIterator.java
index a1915e1..635c6e2 100644
--- a/src/main/java/com/jcabi/dynamo/AwsIterator.java
+++ b/src/main/java/com/jcabi/dynamo/AwsIterator.java
@@ -64,6 +64,7 @@
     (
         of = { "credentials", "conditions", "frame", "name", "keys", "valve" }
     )
+@SuppressWarnings("PMD.GuardLogStatement")
 final class AwsIterator implements Iterator<Item> {
 
     /**
@@ -220,6 +221,8 @@ public void remove() {
 
     /**
      * Dosage with fixed list of items.
+     *
+     * @since 0.1
      */
     @Immutable
     private static final class Fixed implements Dosage {
@@ -227,10 +230,12 @@ private static final class Fixed implements Dosage {
          * List of items.
          */
         private final transient Array<Map<String, AttributeValue>> list;
+
         /**
          * Previous dosage.
          */
         private final transient Dosage prev;
+
         /**
          * Ctor.
          * @param dsg Dosage
@@ -240,14 +245,17 @@ private static final class Fixed implements Dosage {
             this.prev = dsg;
             this.list = new Array<>(items);
         }
+
         @Override
         public List<Map<String, AttributeValue>> items() {
             return Collections.unmodifiableList(this.list);
         }
+
         @Override
         public Dosage next() {
             return this.prev.next();
         }
+
         @Override
         public boolean hasNext() {
             return this.prev.hasNext();
diff --git a/src/main/java/com/jcabi/dynamo/AwsTable.java b/src/main/java/com/jcabi/dynamo/AwsTable.java
index 5a206a4..d79b393 100644
--- a/src/main/java/com/jcabi/dynamo/AwsTable.java
+++ b/src/main/java/com/jcabi/dynamo/AwsTable.java
@@ -63,6 +63,7 @@
 @Loggable(Loggable.DEBUG)
 @ToString
 @EqualsAndHashCode(of = { "credentials", "reg", "self" })
+@SuppressWarnings("PMD.GuardLogStatement")
 final class AwsTable implements Table {
 
     /**
diff --git a/src/main/java/com/jcabi/dynamo/Conditions.java b/src/main/java/com/jcabi/dynamo/Conditions.java
index e6a49fd..65c862a 100644
--- a/src/main/java/com/jcabi/dynamo/Conditions.java
+++ b/src/main/java/com/jcabi/dynamo/Conditions.java
@@ -64,6 +64,7 @@
     (
         {
             "PMD.TooManyMethods",
+            "PMD.ProhibitPublicStaticMethods",
             "PMD.AvoidInstantiatingObjectsInLoops"
         }
     )
diff --git a/src/main/java/com/jcabi/dynamo/Credentials.java b/src/main/java/com/jcabi/dynamo/Credentials.java
index 3829c85..5249133 100644
--- a/src/main/java/com/jcabi/dynamo/Credentials.java
+++ b/src/main/java/com/jcabi/dynamo/Credentials.java
@@ -29,7 +29,6 @@
  */
 package com.jcabi.dynamo;
 
-import com.amazonaws.auth.AWSCredentialsProvider;
 import com.amazonaws.auth.AWSStaticCredentialsProvider;
 import com.amazonaws.auth.BasicAWSCredentials;
 import com.amazonaws.client.builder.AwsClientBuilder;
@@ -82,14 +81,17 @@ final class Simple implements Credentials {
          * AWS key.
          */
         private final transient String key;
+
         /**
          * AWS secret.
          */
         private final transient String secret;
+
         /**
          * Region name.
          */
         private final transient String region;
+
         /**
          * Public ctor, with "us-east-1" region.
          * @param akey AWS key
@@ -98,6 +100,7 @@ final class Simple implements Credentials {
         public Simple(final String akey, final String scrt) {
             this(akey, scrt, Regions.US_EAST_1.getName());
         }
+
         /**
          * Public ctor.
          * @param akey AWS key
@@ -109,10 +112,12 @@ public Simple(final String akey, final String scrt, final String reg) {
             this.secret = scrt;
             this.region = reg;
         }
+
         @Override
         public String toString() {
             return String.format("%s/%s", this.region, this.key);
         }
+
         @Override
         public AmazonDynamoDB aws() {
             final com.amazonaws.regions.Region reg =
@@ -147,12 +152,14 @@ final class Assumed implements Credentials {
          * Region name.
          */
         private final transient String region;
+
         /**
          * Public ctor.
          */
         public Assumed() {
             this(Regions.US_EAST_1.getName());
         }
+
         /**
          * Public ctor.
          * @param reg Region
@@ -160,10 +167,12 @@ public Assumed() {
         public Assumed(final String reg) {
             this.region = reg;
         }
+
         @Override
         public String toString() {
             return this.region;
         }
+
         @Override
         public AmazonDynamoDB aws() {
             final com.amazonaws.regions.Region reg =
@@ -192,10 +201,12 @@ final class Direct implements Credentials {
          * Original credentials.
          */
         private final transient Credentials.Simple origin;
+
         /**
          * Endpoint.
          */
         private final transient String endpoint;
+
         /**
          * Public ctor.
          * @param creds Original credentials
@@ -205,6 +216,7 @@ public Direct(final Credentials.Simple creds, final String pnt) {
             this.origin = creds;
             this.endpoint = pnt;
         }
+
         /**
          * Public ctor.
          * @param creds Original credentials
@@ -213,10 +225,12 @@ public Direct(final Credentials.Simple creds, final String pnt) {
         public Direct(final Credentials.Simple creds, final int port) {
             this(creds, String.format("http://localhost:%d", port));
         }
+
         @Override
         public String toString() {
             return String.format("%s at %s", this.origin, this.endpoint);
         }
+
         @Override
         public AmazonDynamoDB aws() {
             return AmazonDynamoDBClientBuilder.standard()
diff --git a/src/main/java/com/jcabi/dynamo/Dosage.java b/src/main/java/com/jcabi/dynamo/Dosage.java
index 853f920..fb39bce 100644
--- a/src/main/java/com/jcabi/dynamo/Dosage.java
+++ b/src/main/java/com/jcabi/dynamo/Dosage.java
@@ -66,6 +66,8 @@ public interface Dosage {
 
     /**
      * Always empty.
+     *
+     * @since 0.1
      */
     @Immutable
     @Loggable(Loggable.DEBUG)
@@ -76,12 +78,14 @@ final class Empty implements Dosage {
         public List<Map<String, AttributeValue>> items() {
             return new ArrayList<>(0);
         }
+
         @Override
         public Dosage next() {
             throw new IllegalStateException(
                 "this is nothing left"
             );
         }
+
         @Override
         public boolean hasNext() {
             return false;
diff --git a/src/main/java/com/jcabi/dynamo/QueryValve.java b/src/main/java/com/jcabi/dynamo/QueryValve.java
index 8e34c57..9a25607 100644
--- a/src/main/java/com/jcabi/dynamo/QueryValve.java
+++ b/src/main/java/com/jcabi/dynamo/QueryValve.java
@@ -62,7 +62,7 @@
 @ToString
 @Loggable(Loggable.DEBUG)
 @EqualsAndHashCode(of = { "limit", "forward" })
-@SuppressWarnings("PMD.TooManyMethods")
+@SuppressWarnings({"PMD.TooManyMethods", "PMD.GuardLogStatement"})
 public final class QueryValve implements Valve {
 
     /**
@@ -339,6 +339,8 @@ public QueryValve withAttributesToGet(final String... names) {
 
     /**
      * Next dosage.
+     *
+     * @since 0.1
      */
     @ToString
     @Loggable(Loggable.DEBUG)
@@ -348,14 +350,17 @@ private final class NextDosage implements Dosage {
          * AWS client.
          */
         private final transient Credentials credentials;
+
         /**
          * Query request.
          */
         private final transient QueryRequest request;
+
         /**
          * Query request.
          */
         private final transient QueryResult result;
+
         /**
          * Public ctor.
          * @param creds Credentials
@@ -368,14 +373,17 @@ private final class NextDosage implements Dosage {
             this.request = rqst;
             this.result = rslt;
         }
+
         @Override
         public List<Map<String, AttributeValue>> items() {
             return this.result.getItems();
         }
+
         @Override
         public boolean hasNext() {
             return this.result.getLastEvaluatedKey() != null;
         }
+
         @Override
         public Dosage next() {
             if (!this.hasNext()) {
diff --git a/src/main/java/com/jcabi/dynamo/Region.java b/src/main/java/com/jcabi/dynamo/Region.java
index 2d03818..baa8e98 100644
--- a/src/main/java/com/jcabi/dynamo/Region.java
+++ b/src/main/java/com/jcabi/dynamo/Region.java
@@ -74,6 +74,8 @@ public interface Region {
 
     /**
      * Simple region, basic implementation.
+     *
+     * @since 0.1
      */
     @Immutable
     @Loggable(Loggable.DEBUG)
@@ -84,6 +86,7 @@ final class Simple implements Region {
          * Credentials.
          */
         private final transient Credentials credentials;
+
         /**
          * Public ctor.
          * @param creds Credentials
@@ -91,10 +94,12 @@ final class Simple implements Region {
         public Simple(final Credentials creds) {
             this.credentials = creds;
         }
+
         @Override
         public AmazonDynamoDB aws() {
             return this.credentials.aws();
         }
+
         @Override
         public Table table(final String name) {
             return new AwsTable(this.credentials, this, name);
@@ -116,6 +121,8 @@ public Table table(final String name) {
      * instance pointing to the Dynamo DB table named {@code "foo-test"}. Could
      * be a convenient mechanism when you have many tables for different
      * projects in the same region.
+     *
+     * @since 0.1
      */
     @Immutable
     @Loggable(Loggable.DEBUG)
@@ -126,10 +133,12 @@ final class Prefixed implements Region {
          * Original region.
          */
         private final transient Region origin;
+
         /**
          * Prefix to add.
          */
         private final transient String prefix;
+
         /**
          * Public ctor.
          * @param region Original region
@@ -139,10 +148,12 @@ public Prefixed(final Region region, final String pfx) {
             this.origin = region;
             this.prefix = pfx;
         }
+
         @Override
         public AmazonDynamoDB aws() {
             return this.origin.aws();
         }
+
         @Override
         public Table table(final String name) {
             return this.origin.table(
diff --git a/src/main/java/com/jcabi/dynamo/ScanValve.java b/src/main/java/com/jcabi/dynamo/ScanValve.java
index 722354f..8047d83 100644
--- a/src/main/java/com/jcabi/dynamo/ScanValve.java
+++ b/src/main/java/com/jcabi/dynamo/ScanValve.java
@@ -62,6 +62,7 @@
 @ToString
 @Loggable(Loggable.DEBUG)
 @EqualsAndHashCode(of = { "limit", "attributes" })
+@SuppressWarnings("PMD.GuardLogStatement")
 public final class ScanValve implements Valve {
 
     /**
@@ -208,6 +209,8 @@ public ScanValve withAttributeToGet(final String... names) {
 
     /**
      * Next dosage.
+     *
+     * @since 0.1
      */
     @ToString
     @Loggable(Loggable.DEBUG)
@@ -217,14 +220,17 @@ private final class NextDosage implements Dosage {
          * AWS client.
          */
         private final transient Credentials credentials;
+
         /**
          * Query request.
          */
         private final transient ScanRequest request;
+
         /**
          * Query request.
          */
         private final transient ScanResult result;
+
         /**
          * Public ctor.
          * @param creds Credentials
@@ -237,14 +243,17 @@ private final class NextDosage implements Dosage {
             this.request = rqst;
             this.result = rslt;
         }
+
         @Override
         public List<Map<String, AttributeValue>> items() {
             return this.result.getItems();
         }
+
         @Override
         public boolean hasNext() {
             return this.result.getLastEvaluatedKey() != null;
         }
+
         @Override
         public Dosage next() {
             if (!this.hasNext()) {
diff --git a/src/main/java/com/jcabi/dynamo/mock/H2Data.java b/src/main/java/com/jcabi/dynamo/mock/H2Data.java
index f40de58..5da0050 100644
--- a/src/main/java/com/jcabi/dynamo/mock/H2Data.java
+++ b/src/main/java/com/jcabi/dynamo/mock/H2Data.java
@@ -75,28 +75,6 @@
 @SuppressWarnings({ "PMD.TooManyMethods", "PMD.ExcessiveImports" })
 public final class H2Data implements MkData {
 
-    /**
-     * Create primary key.
-     */
-    private static final Function<String, String> CREATE_KEY =
-        key -> String.format("%s VARCHAR PRIMARY KEY", key);
-
-    /**
-     * Create attr.
-     */
-    private static final Function<String, String> CREATE_ATTR =
-        key -> String.format("%s CLOB", key);
-
-    /**
-     * WHERE clauses are joined with this.
-     */
-    private static final String AND = " AND ";
-
-    /**
-     * JDBC URL.
-     */
-    private final transient String jdbc;
-
     /**
      * Fetcher of rows.
      */
@@ -112,6 +90,7 @@ public Iterable<Attributes> handle(final ResultSet rset,
                 }
                 return items;
             }
+
             /**
              * Convert result set to Attributes.
              * @param rset Result set
@@ -172,6 +151,28 @@ private Attributes fetch(final ResultSet rset) throws SQLException {
         );
     };
 
+    /**
+     * Create primary key.
+     */
+    private static final Function<String, String> CREATE_KEY =
+        key -> String.format("%s VARCHAR PRIMARY KEY", key);
+
+    /**
+     * Create attr.
+     */
+    private static final Function<String, String> CREATE_ATTR =
+        key -> String.format("%s CLOB", key);
+
+    /**
+     * WHERE clauses are joined with this.
+     */
+    private static final String AND = " AND ";
+
+    /**
+     * JDBC URL.
+     */
+    private final transient String jdbc;
+
     /**
      * Public ctor.
      * @throws IOException If fails
@@ -349,6 +350,7 @@ public H2Data with(final String table, final String[] keys,
         }
         return this;
     }
+
     /**
      * Make data source.
      * @return Data source for JDBC
diff --git a/src/main/java/com/jcabi/dynamo/mock/MkTable.java b/src/main/java/com/jcabi/dynamo/mock/MkTable.java
index 373f9c1..b9e8c62 100644
--- a/src/main/java/com/jcabi/dynamo/mock/MkTable.java
+++ b/src/main/java/com/jcabi/dynamo/mock/MkTable.java
@@ -65,8 +65,8 @@ final class MkTable implements Table {
 
     /**
      * Public ctor.
-     * @param name Name of the table
      * @param dta Data
+     * @param name Name of the table
      */
     MkTable(final MkData dta, final String name) {
         this.data = dta;
diff --git a/src/test/java/com/jcabi/dynamo/AwsTableTest.java b/src/test/java/com/jcabi/dynamo/AwsTableTest.java
index 74c2d77..0313b51 100644
--- a/src/test/java/com/jcabi/dynamo/AwsTableTest.java
+++ b/src/test/java/com/jcabi/dynamo/AwsTableTest.java
@@ -56,6 +56,7 @@ public final class AwsTableTest {
      * Constant for 'tableName' attribute.
      */
     private static final String TABLE_NAME = "tableName";
+
     /**
      * Constant for 'key' attribute.
      */
diff --git a/src/test/java/com/jcabi/dynamo/mock/H2DataTest.java b/src/test/java/com/jcabi/dynamo/mock/H2DataTest.java
index c7d3f61..1403103 100644
--- a/src/test/java/com/jcabi/dynamo/mock/H2DataTest.java
+++ b/src/test/java/com/jcabi/dynamo/mock/H2DataTest.java
@@ -81,6 +81,7 @@ table, new Conditions().with(key, Conditions.equalTo(number))
 
     /**
      * H2Data can store to a file.
+     * @param temp Temp dir
      * @throws Exception If some problem inside
      * @see <a href="https://code.google.com/p/h2database/issues/detail?id=447">
      *  Google Code: DB file extension customizability</a>
diff --git a/src/test/java/com/jcabi/dynamo/mock/MkRegionTest.java b/src/test/java/com/jcabi/dynamo/mock/MkRegionTest.java
index c2fbaf2..54b37d1 100644
--- a/src/test/java/com/jcabi/dynamo/mock/MkRegionTest.java
+++ b/src/test/java/com/jcabi/dynamo/mock/MkRegionTest.java
@@ -104,7 +104,7 @@ public void storesAndReadsSingleAttribute() throws Exception {
         final Table tbl = region.table(table);
         tbl.put(
             new Attributes()
-                .with(key, "32443")
+                .with(key, "324439")
                 .with(attr, "0")
         );
         final Item item = tbl.frame().iterator().next();