diff --git a/README.md b/README.md
index ceeef98..99f8cb9 100644
--- a/README.md
+++ b/README.md
@@ -40,6 +40,7 @@ soramitsu {
     # path to output JAR which is going to be dockerized
     jar = jar = new File("build/libs/${project.name}-${project.version}.jar") 
     # manually specified docker tag. if null, automatic versioning based on git is used 
+    # it replaces only 'version' part, e.g. ${name}:${tag}. Example: soramitsu/example:${tag}
     tag = "custom-tag"  
     # to enable dockerPush task, define registry credentials
     registry {
diff --git a/gradle/wrapper/gradle-wrapper.properties b/gradle/wrapper/gradle-wrapper.properties
index 115e6ac..f4d7b2b 100644
--- a/gradle/wrapper/gradle-wrapper.properties
+++ b/gradle/wrapper/gradle-wrapper.properties
@@ -1,5 +1,5 @@
 distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-4.10-bin.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-5.4.1-bin.zip
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists
diff --git a/src/test/groovy/jp/co/soramitsu/devops/misc/ExtensionTest.groovy b/src/test/groovy/jp/co/soramitsu/devops/misc/ExtensionTest.groovy
index 91d8262..d35e7b3 100644
--- a/src/test/groovy/jp/co/soramitsu/devops/misc/ExtensionTest.groovy
+++ b/src/test/groovy/jp/co/soramitsu/devops/misc/ExtensionTest.groovy
@@ -82,13 +82,13 @@ class ExtensionTest extends Specification {
             }
             group = 'group'
             
-            
             soramitsu {
               projectGroup = '${projectGroup}'
               docker {
-                tag = '${tag}'
+                tag = "${tag}"
                 jar = new File('${jar}')
-                registry {}
+                registry {
+                }
               }
             }
         """
diff --git a/src/test/groovy/jp/co/soramitsu/devops/utils/GradleProjectExecutor.groovy b/src/test/groovy/jp/co/soramitsu/devops/utils/GradleProjectExecutor.groovy
index fc9036e..e98cc13 100644
--- a/src/test/groovy/jp/co/soramitsu/devops/utils/GradleProjectExecutor.groovy
+++ b/src/test/groovy/jp/co/soramitsu/devops/utils/GradleProjectExecutor.groovy
@@ -6,6 +6,8 @@ import org.gradle.testkit.runner.GradleRunner
 import org.slf4j.Logger
 import org.slf4j.LoggerFactory
 
+import java.util.function.BiConsumer
+
 
 class GradleProjectExecutor {