Add API 31 sources

Test: None
Change-Id: Ie45894f7a232b2a15e2439b2527ca1813f334cc5

mypackage/MockFileSystem.java

diff --git a/mypackage/MockFileSystem.java b/mypackage/MockFileSystem.java
new file mode 100644
index 0000000..6981186
--- /dev/null
+++ b/mypackage/MockFileSystem.java
@@ -0,0 +1,117 @@
+/*
+ * Copyright (C) 2017 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License
+ */
+
+package mypackage;
+
+import java.io.IOException;
+import java.net.URI;
+import java.nio.file.FileStore;
+import java.nio.file.FileSystem;
+import java.nio.file.Path;
+import java.nio.file.PathMatcher;
+import java.nio.file.WatchService;
+import java.nio.file.attribute.UserPrincipalLookupService;
+import java.nio.file.spi.FileSystemProvider;
+import java.util.Map;
+import java.util.Set;
+
+public class MockFileSystem extends FileSystem {
+    private URI uri;
+    private Map<String, ?> env;
+    private Path path;
+
+    public MockFileSystem(URI uri, Map<String, ?> env) {
+        this.uri = uri;
+        this.env = env;
+    }
+
+    public MockFileSystem(Path path, Map<String, ?> env) {
+        this.path = path;
+        this.env = env;
+    }
+
+    public URI getURI() {
+        return uri;
+    }
+
+    public Path getPath() {
+        return path;
+    }
+
+    public Map<String, ?> getEnv() {
+        return env;
+    }
+
+    @Override
+    public FileSystemProvider provider() {
+        return null;
+    }
+
+    @Override
+    public void close() throws IOException {
+
+    }
+
+    @Override
+    public boolean isOpen() {
+        return false;
+    }
+
+    @Override
+    public boolean isReadOnly() {
+        return false;
+    }
+
+    @Override
+    public String getSeparator() {
+        return null;
+    }
+
+    @Override
+    public Iterable<Path> getRootDirectories() {
+        return null;
+    }
+
+    @Override
+    public Iterable<FileStore> getFileStores() {
+        return null;
+    }
+
+    @Override
+    public Set<String> supportedFileAttributeViews() {
+        return null;
+    }
+
+    @Override
+    public Path getPath(String first, String... more) {
+        return null;
+    }
+
+    @Override
+    public PathMatcher getPathMatcher(String syntaxAndPattern) {
+        return null;
+    }
+
+    @Override
+    public UserPrincipalLookupService getUserPrincipalLookupService() {
+        return null;
+    }
+
+    @Override
+    public WatchService newWatchService() throws IOException {
+        return null;
+    }
+}