Gradle 6.0 compatibility by removing deprecated API

build.gradle

@@ -1,6 +1,6 @@
 plugins {
-    id "com.gradle.plugin-publish" version "0.9.4"
-    id "com.jfrog.bintray" version "1.6"
+    id "com.gradle.plugin-publish" version "0.10.1"
+    id "com.jfrog.bintray" version "1.8.4"
 }
 
 apply plugin: 'groovy'
@@ -10,8 +10,8 @@ apply plugin: 'signing'
 apply plugin: 'idea'
 apply plugin: 'jacoco'
 
-sourceCompatibility = 1.6
-targetCompatibility = 1.6
+sourceCompatibility = 1.7
+targetCompatibility = 1.7
 
 defaultTasks 'clean', 'build'
 
@@ -225,6 +225,14 @@ def getPomConfiguration() {
 // download dependencies all at once, keeps downloads out of travis output
 task resolveAllDependencies {
     doLast {
-        configurations.all { it.resolve() }
+        configurations.all { configuration ->
+            if (configuration.isCanBeResolved()) {
+                println "Resolving $configuration"
+                configuration.resolve()
+            }
+            else {
+                println "$configuration is not resolvable"
+            }
+        }
     }
-}
+}

gradle/wrapper/gradle-wrapper.properties

@@ -3,4 +3,4 @@ distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-4.0.1-bin.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-5.3.1-bin.zip

src/main/groovy/com/eriwen/gradle/css/source/internal/DefaultCssSourceSetContainer.java

@@ -4,6 +4,7 @@
 import com.eriwen.gradle.css.source.CssSourceSetContainer;
 import org.gradle.api.Project;
 import org.gradle.api.internal.AbstractNamedDomainObjectContainer;
+import org.gradle.api.internal.CollectionCallbackActionDecorator;
 import org.gradle.api.internal.file.FileResolver;
 import org.gradle.internal.reflect.Instantiator;
 
@@ -14,7 +15,7 @@ public class DefaultCssSourceSetContainer extends AbstractNamedDomainObjectConta
     private final FileResolver fileResolver;
 
     public DefaultCssSourceSetContainer(Project project, Instantiator instantiator, FileResolver fileResolver) {
-        super(CssSourceSet.class, instantiator);
+        super(CssSourceSet.class, instantiator, CollectionCallbackActionDecorator.NOOP);
         this.project = project;
         this.instantiator = instantiator;
         this.fileResolver = fileResolver;