diff --git a/core/che-core-api-core/src/main/java/org/eclipse/che/api/core/Page.java b/core/che-core-api-core/src/main/java/org/eclipse/che/api/core/Page.java
index 193afb3ed4..bcbebbcf2c 100644
--- a/core/che-core-api-core/src/main/java/org/eclipse/che/api/core/Page.java
+++ b/core/che-core-api-core/src/main/java/org/eclipse/che/api/core/Page.java
@@ -91,6 +91,11 @@ public class Page<ITEM_T> {
   private final long totalCount;
   private final List<ITEM_T> items;
 
+  final String nonNullItemsString = "Required non-null items";
+  final String nonNegativeValueOfItems = "Required non-negative value of items before";
+  final String positiveValueOfPageSize = "Required positive value of page size";
+  final String nonNegativeValueOfTotalItems = "Required non-negative value of total items";
+
   /**
    * Creates a new page.
    *
@@ -104,13 +109,13 @@ public class Page<ITEM_T> {
    * @throws IllegalArgumentException when {@code totalCount} is negative
    */
   public Page(Collection<? extends ITEM_T> items, long itemsBefore, int pageSize, long totalCount) {
-    requireNonNull(items, "Required non-null items");
+    requireNonNull(items, nonNullItemsString);
     this.items = new ArrayList<>(items);
-    checkArgument(itemsBefore >= 0, "Required non-negative value of items before");
+    checkArgument(itemsBefore >= 0, nonNegativeValueOfItems);
     this.itemsBefore = itemsBefore;
-    checkArgument(pageSize > 0, "Required positive value of page size");
+    checkArgument(pageSize > 0, positiveValueOfPageSize);
     this.pageSize = pageSize;
-    checkArgument(totalCount >= 0, "Required non-negative value of total items");
+    checkArgument(totalCount >= 0, nonNegativeValueOfTotalItems);
     this.totalCount = totalCount;
   }
 
diff --git a/core/che-core-api-core/src/main/java/org/eclipse/che/api/core/jsonrpc/commons/transmission/EndpointIdConfigurator.java b/core/che-core-api-core/src/main/java/org/eclipse/che/api/core/jsonrpc/commons/transmission/EndpointIdConfigurator.java
index be2fa3323b..a64de84fe3 100644
--- a/core/che-core-api-core/src/main/java/org/eclipse/che/api/core/jsonrpc/commons/transmission/EndpointIdConfigurator.java
+++ b/core/che-core-api-core/src/main/java/org/eclipse/che/api/core/jsonrpc/commons/transmission/EndpointIdConfigurator.java
@@ -21,6 +21,10 @@ import org.eclipse.che.api.core.jsonrpc.commons.ResponseDispatcher;
 import org.eclipse.che.api.core.websocket.commons.WebSocketMessageTransmitter;
 import org.slf4j.Logger;
 
+private static final String endpointIdMustNotBeNull = "Endpoint ID must not be null"
+private static final String endpointIdMustNotBeEmpty = "Endpoint ID must not be empty"
+
+
 /** Endpoint ID configurator to defined endpoint id that the request should be addressed to. */
 public class EndpointIdConfigurator {
   private static final Logger LOGGER = getLogger(EndpointIdConfigurator.class);
@@ -40,8 +44,8 @@ public class EndpointIdConfigurator {
   }
 
   public MethodNameConfigurator endpointId(String id) {
-    checkNotNull(id, "Endpoint ID must not be null");
-    checkArgument(!id.isEmpty(), "Endpoint ID must not be empty");
+    checkNotNull(id, endpointIdMustNotBeNull);
+    checkArgument(!id.isEmpty(), endpointIdMustNotBeEmpty);
 
     LOGGER.debug("Configuring outgoing request endpoint ID: " + id);
 
diff --git a/core/che-core-api-core/src/main/java/org/eclipse/che/api/core/jsonrpc/commons/transmission/SendConfiguratorFromOne.java b/core/che-core-api-core/src/main/java/org/eclipse/che/api/core/jsonrpc/commons/transmission/SendConfiguratorFromOne.java
index 24c2bfcd20..f11239baba 100644
--- a/core/che-core-api-core/src/main/java/org/eclipse/che/api/core/jsonrpc/commons/transmission/SendConfiguratorFromOne.java
+++ b/core/che-core-api-core/src/main/java/org/eclipse/che/api/core/jsonrpc/commons/transmission/SendConfiguratorFromOne.java
@@ -41,6 +41,8 @@ public class SendConfiguratorFromOne<P> {
   private final P pValue;
   private final String endpointId;
 
+  private static final String resultClassMustNotBeNull= "Result class value must not be null";
+
   SendConfiguratorFromOne(
       JsonRpcMarshaller marshaller,
       ResponseDispatcher dispatcher,
@@ -79,7 +81,7 @@ public class SendConfiguratorFromOne<P> {
 
   public <R> JsonRpcPromise<R> sendAndReceiveResultAsDto(
       final Class<R> rClass, int timeoutInMillis) {
-    checkNotNull(rClass, "Result class value must not be null");
+    checkNotNull(rClass, resultClassMustNotBeNull);
 
     final String requestId = transmitRequest();
 
diff --git a/core/che-core-api-dto-maven-plugin/src/main/java/org/eclipse/che/dto/generator/maven/plugin/DtoGeneratorMojo.java b/core/che-core-api-dto-maven-plugin/src/main/java/org/eclipse/che/dto/generator/maven/plugin/DtoGeneratorMojo.java
index 122afccff3..e186e5f30e 100644
--- a/core/che-core-api-dto-maven-plugin/src/main/java/org/eclipse/che/dto/generator/maven/plugin/DtoGeneratorMojo.java
+++ b/core/che-core-api-dto-maven-plugin/src/main/java/org/eclipse/che/dto/generator/maven/plugin/DtoGeneratorMojo.java
@@ -19,6 +19,8 @@ import org.apache.maven.plugins.annotations.Parameter;
 import org.apache.maven.plugins.annotations.ResolutionScope;
 import org.eclipse.che.dto.generator.DtoGenerator;
 
+
+
 /** Mojo to run {@link org.eclipse.che.dto.generator.DtoGenerator}. */
 @Mojo(name = "generate", requiresDependencyResolution = ResolutionScope.COMPILE)
 public class DtoGeneratorMojo extends AbstractMojo {
@@ -38,10 +40,12 @@ public class DtoGeneratorMojo extends AbstractMojo {
   @Parameter(property = "che.dto.skip", defaultValue = "false")
   private boolean skip;
 
+  private static String skippingTheExecution= "Skipping the execution";
+
   @Override
   public void execute() throws MojoExecutionException {
     if (skip) {
-      getLog().info("Skipping the execution");
+      getLog().info(skippingTheExecution);
       return;
     }
 
diff --git a/core/che-core-metrics-core/src/main/java/org/eclipse/che/core/metrics/FileStoresMeterBinder.java b/core/che-core-metrics-core/src/main/java/org/eclipse/che/core/metrics/FileStoresMeterBinder.java
index 0febd2fe9c..cb1573ee1b 100644
--- a/core/che-core-metrics-core/src/main/java/org/eclipse/che/core/metrics/FileStoresMeterBinder.java
+++ b/core/che-core-metrics-core/src/main/java/org/eclipse/che/core/metrics/FileStoresMeterBinder.java
@@ -29,6 +29,7 @@ import org.slf4j.LoggerFactory;
 public class FileStoresMeterBinder implements MeterBinder {
 
   private static final Logger LOG = LoggerFactory.getLogger(FileStoresMeterBinder.class);
+  private static final String  unallocatedSpaceForFileStorage = "Unallocated space for file storage"
 
   @Override
   public void bindTo(MeterRegistry registry) {
@@ -42,7 +43,7 @@ public class FileStoresMeterBinder implements MeterBinder {
 
       Gauge.builder("disk.free", fileStore, exceptionToNonWrapper(FileStore::getUnallocatedSpace))
           .tags(tagsWithPath)
-          .description("Unallocated space for file storage")
+          .description(unallocatedSpaceForFileStorage)
           .baseUnit("bytes")
           .strongReference(true)
           .register(registry);