}

    public static <T> T nonNull(T obj, String message) {
        if (obj == null) {
            throw new IllegalArgumentException(message);
        }
        return obj;
    }

    protected static <T> Collection<T> unmodifiable(Collection<T> obj) {
        return obj != null && !obj.isEmpty()
                ? Collections.unmodifiableCollection(new ArrayList<>(obj))
                : Collections.emptyList();
    }

            return hashCode;
        }

        @Override
        public boolean equals(Object obj) {
            if (this == obj) {
                return true;
            }

            if (!(obj instanceof CacheKey)) {
                return false;
            }

            CacheKey that = (CacheKey) obj;

            return Objects.equals(this.artifactId, that.artifactId)

    }

    @Override
    public boolean equals(Object obj) {
        if (this == obj) {
            return true;
        }

        if (obj == null) {
            return false;
        }

        if (!UrlSource.class.equals(obj.getClass())) {
            return false;
        }

        UrlSource other = (UrlSource) obj;
        return Objects.equals(url.toExternalForm(), other.url.toExternalForm());

    }

    @Override
    public boolean equals(Object obj) {
        if (this == obj) {
            return true;
        }

        if (obj == null) {
            return false;
        }

        if (!FileSource.class.equals(obj.getClass())) {
            return false;
        }

        FileSource other = (FileSource) obj;
        return this.path.equals(other.path);
    }

        return hash;
    }

    @Override
    public boolean equals(Object obj) {
        if (this == obj) {
            return true;
        }

        if (!(obj instanceof ExclusionSetFilter)) {
            return false;
        }

        ExclusionSetFilter other = (ExclusionSetFilter) obj;

        return excludes.equals(other.excludes);
    }

     *
     * @param obj The object to create a string representation for, may be <code>null</code>.
     * @return The string representation, never <code>null</code>.
     */
    private String toString(Object obj) {
        String str;
        if (obj != null && obj.getClass().isArray()) {
            int n = Array.getLength(obj);
            StringBuilder buf = new StringBuilder(256);

        }

        @Override
        public boolean equals(Object obj) {
            if (this == obj) {
                return true;
            }
            if (null == obj || !getClass().equals(obj.getClass())) {
                return false;
            }
            GavCacheKey that = (GavCacheKey) obj;
            return Objects.equals(this.gav, that.gav) && Objects.equals(this.tag, that.tag);

    }

    @Override
    public boolean equals(Object obj) {
        if (obj == null) {
            return false;
        }

        if (this == obj) {
            return true;
        }

        if (!(obj instanceof DefaultToolchain)) {
            return false;
        }

        DefaultToolchain other = (DefaultToolchain) obj;

        if (!Objects.equals(type, other.type)) {

        public String getContentType() {
            return type;
        }

        public boolean equals(Object obj) {
            if (this == obj) {
                return true;
            } else {
                return obj != null && this.getClass().equals(obj.getClass()) && this.keys.equals(((Key) obj).keys);
            }
        }

        public int hashCode() {
            return this.keys.hashCode();

        }

        @Override
        public boolean equals(Object obj) {
            if (this == obj) {
                return true;
            }
            if (!(obj instanceof GAKey)) {
                return false;
            }
            GAKey that = (GAKey) obj;
            return artifactId.equals(that.artifactId) && groupId.equals(that.groupId);
        }