expect:
        fileTree.getBuiltBy().empty

        when:
        fileTree.builtBy("a")
        fileTree.builtBy("b")
        fileTree.from("f")
        then:
        fileTree.getBuiltBy() == ["a", "b"] as Set
        dep.mutableValues == ["a", "b"] as Set

        when:
        fileTree.setBuiltBy(["c"])
        then:
        fileTree.getBuiltBy() == ["c"] as Set

    }

    @Override
    public ConfigurableFileTree builtBy(Object... tasks) {
        buildDependency.add(tasks);
        return this;
    }

    @Override
    public Set<Object> getBuiltBy() {
        return buildDependency.getMutableValues();
    }

    @Override
    public ConfigurableFileTree setBuiltBy(Iterable<?> tasks) {
        buildDependency.setValues(tasks);
        return this;

    /**
     * Returns the set of tasks which build the files of this collection.
     *
     * @return The set. Returns an empty set when there are no such tasks.
     */
    Set<Object> getBuiltBy();

    /**
     * Sets the tasks which build the files of this collection.
     *
     * @param tasks The tasks. These are evaluated as per {@link org.gradle.api.Task#dependsOn(Object...)}.
     * @return this

    /**
     * Returns the set of tasks which build the files of this collection.
     *
     * @return The set. Returns an empty set when there are no such tasks.
     */
    Set<Object> getBuiltBy();

    /**
     * Sets the tasks which build the files of this collection.
     *
     * @param tasks The tasks. These are evaluated as per {@link org.gradle.api.Task#dependsOn(Object...)}.
     * @return this

    }

    @Override
    public ConfigurableFileCollection builtBy(Object... tasks) {
        buildDependency.add(tasks);
        return this;
    }

    @Override
    public Set<Object> getBuiltBy() {
        return buildDependency.getMutableValues();
    }

    @Override
    public ConfigurableFileCollection setBuiltBy(Iterable<?> tasks) {
        buildDependency.setValues(tasks);
        return this;

Method <org.gradle.api.credentials.PasswordCredentials.getUsername()> does not have raw return type assignable to org.gradle.api.provider.Property in (PasswordCredentials.java:0)
Method <org.gradle.api.file.ConfigurableFileTree.getBuiltBy()> does not have raw return type assignable to org.gradle.api.provider.Property in (ConfigurableFileTree.java:0)