Fix for shadowJar out-of-date with configuration caching

src/main/groovy/com/github/jengelman/gradle/plugins/shadow/internal/AbstractDependencyFilter.groovy

@@ -2,7 +2,6 @@ package com.github.jengelman.gradle.plugins.shadow.internal
 
 import groovy.util.logging.Slf4j
 import org.gradle.api.Project
-import org.gradle.api.artifacts.Configuration
 import org.gradle.api.artifacts.Dependency
 import org.gradle.api.artifacts.ResolvedDependency
 import org.gradle.api.file.FileCollection
@@ -25,7 +24,7 @@ abstract class AbstractDependencyFilter implements DependencyFilter {
                                     Set<ResolvedDependency> includedDependencies,
                                     Set<ResolvedDependency> excludedDependencies)
 
-    FileCollection resolve(Configuration configuration) {
+    FileCollection resolve(FileCollection configuration) {
         Set<ResolvedDependency> includedDeps = []
         Set<ResolvedDependency> excludedDeps = []
         resolve(configuration.resolvedConfiguration.firstLevelModuleDependencies, includedDeps, excludedDeps)
@@ -34,7 +33,7 @@ abstract class AbstractDependencyFilter implements DependencyFilter {
         }.flatten())
     }
 
-    FileCollection resolve(Collection<Configuration> configurations) {
+    FileCollection resolve(Collection<FileCollection> configurations) {
         configurations.collect {
             resolve(it)
         }.sum() as FileCollection ?: project.files()

src/main/groovy/com/github/jengelman/gradle/plugins/shadow/internal/DependencyFilter.groovy

@@ -1,6 +1,5 @@
 package com.github.jengelman.gradle.plugins.shadow.internal
 
-import org.gradle.api.artifacts.Configuration
 import org.gradle.api.artifacts.Dependency
 import org.gradle.api.artifacts.ResolvedDependency
 import org.gradle.api.file.FileCollection
@@ -9,18 +8,18 @@ import org.gradle.api.specs.Spec
 interface DependencyFilter {
 
     /**
-     * Resolve a Configuration against the include/exclude rules in the filter
+     * Resolve a FileCollection against the include/exclude rules in the filter
      * @param configuration
      * @return
      */
-    FileCollection resolve(Configuration configuration)
+    FileCollection resolve(FileCollection configuration)
 
     /**
-     * Resolve all Configurations against the include/exclude ruels in the filter and combine the results
+     * Resolve all FileCollections against the include/exclude ruels in the filter and combine the results
      * @param configurations
      * @return
      */
-    FileCollection resolve(Collection<Configuration> configurations)
+    FileCollection resolve(Collection<FileCollection> configurations)
 
     /**
      * Exclude dependencies that match the provided spec.

src/main/groovy/com/github/jengelman/gradle/plugins/shadow/tasks/ShadowJar.java

@@ -31,7 +31,7 @@ public class ShadowJar extends Jar implements ShadowSpec {
 
     private List<Transformer> transformers;
     private List<Relocator> relocators;
-    private transient List<Configuration> configurations;
+    private List<FileCollection> configurations;
     private transient DependencyFilter dependencyFilter;
 
     private boolean minimizeJar;
@@ -429,11 +429,11 @@ public void setRelocators(List<Relocator> relocators) {
     }
 
     @Classpath @Optional
-    public List<Configuration> getConfigurations() {
+    public List<FileCollection> getConfigurations() {
         return this.configurations;
     }
 
-    public void setConfigurations(List<Configuration> configurations) {
+    public void setConfigurations(List<FileCollection> configurations) {
         this.configurations = configurations;
     }
 

src/test/groovy/com/github/jengelman/gradle/plugins/shadow/ConfigurationCacheSpec.groovy

@@ -132,4 +132,38 @@ class ConfigurationCacheSpec extends PluginSpecification {
         and:
         result.output.contains("Reusing configuration cache.")
     }
+
+    def "configuration caching of configurations is up-to-date"() {
+        given:
+        file('settings.gradle') << """
+            include 'lib'
+        """.stripIndent()
+
+        and:
+        file('lib/src/main/java/lib/Lib.java') << """
+            package lib;
+            public class Lib {}
+        """.stripIndent()
+        file('lib/build.gradle') << """
+            apply plugin: 'java'
+            apply plugin: 'com.github.johnrengelman.shadow'
+
+            repositories { maven { url "${repo.uri}" } }
+            dependencies {
+                implementation "junit:junit:3.8.2"
+            }
+
+            shadowJar {
+                configurations = [project.configurations.compileClasspath]
+            }
+
+        """.stripIndent()
+
+        when:
+        run('--configuration-cache', 'shadowJar', '-s')
+        def result = run('--configuration-cache', 'shadowJar', '-s')
+
+        then:
+        result.output.contains(":lib:shadowJar UP-TO-DATE")
+    }
 }