diff --git a/guacamole-common-js/src/main/webapp/modules/AudioPlayer.js b/guacamole-common-js/src/main/webapp/modules/AudioPlayer.js
index 9cc6b3a3c..0097355f9 100644
--- a/guacamole-common-js/src/main/webapp/modules/AudioPlayer.js
+++ b/guacamole-common-js/src/main/webapp/modules/AudioPlayer.js
@@ -261,7 +261,7 @@ Guacamole.RawAudioPlayer = function RawAudioPlayer(stream, mimetype) {
      * @param {SampleArray} data
      *     The audio packet to split.
      *
-     * @returns {SampleArray[]}
+     * @returns {!SampleArray[]}
      *     An array of audio packets containing the result of splitting the
      *     provided audio packet. If splitting is possible, this array will
      *     contain two packets. If splitting is not possible, this array will
@@ -371,7 +371,7 @@ Guacamole.RawAudioPlayer = function RawAudioPlayer(stream, mimetype) {
      *     The raw audio packet that should be converted into a Web Audio API
      *     AudioBuffer.
      *
-     * @returns {AudioBuffer}
+     * @returns {!AudioBuffer}
      *     A new Web Audio API AudioBuffer containing the provided audio data,
      *     converted to the format used by the Web Audio API.
      */
@@ -463,7 +463,7 @@ Guacamole.RawAudioPlayer.prototype = new Guacamole.AudioPlayer();
  * @param {String} mimetype
  *     The mimetype to check.
  *
- * @returns {Boolean}
+ * @returns {boolean}
  *     true if the given mimetype is supported by Guacamole.RawAudioPlayer,
  *     false otherwise.
  */
@@ -485,7 +485,7 @@ Guacamole.RawAudioPlayer.isSupportedType = function isSupportedType(mimetype) {
  * additional parameters. Something like "audio/L8;rate=44100" would be valid,
  * however (see https://tools.ietf.org/html/rfc4856).
  *
- * @returns {String[]}
+ * @returns {string[]}
  *     A list of all mimetypes supported by Guacamole.RawAudioPlayer, excluding
  *     any parameters. If the necessary JavaScript APIs for playing raw audio
  *     are absent, this list will be empty.
diff --git a/guacamole-common-js/src/main/webapp/modules/AudioRecorder.js b/guacamole-common-js/src/main/webapp/modules/AudioRecorder.js
index 7a1df8be8..2f28ee6c9 100644
--- a/guacamole-common-js/src/main/webapp/modules/AudioRecorder.js
+++ b/guacamole-common-js/src/main/webapp/modules/AudioRecorder.js
@@ -278,7 +278,7 @@ Guacamole.RawAudioRecorder = function RawAudioRecorder(stream, mimetype) {
      * @param {Number} x
      *     The point at which the normalized sinc function should be computed.
      *
-     * @returns {Number}
+     * @returns {number}
      *     The value of the normalized sinc function at x.
      */
     var sinc = function sinc(x) {
@@ -305,7 +305,7 @@ Guacamole.RawAudioRecorder = function RawAudioRecorder(stream, mimetype) {
      * @param {Number} a
      *     The window size to use for the Lanczos kernel.
      *
-     * @returns {Number}
+     * @returns {number}
      *     The value of the Lanczos kernel at the given point for the given
      *     window size.
      */
@@ -336,7 +336,7 @@ Guacamole.RawAudioRecorder = function RawAudioRecorder(stream, mimetype) {
      *     0 and 1 inclusive, where 0 represents the earliest point in time and
      *     1 represents the latest.
      *
-     * @returns {Number}
+     * @returns {number}
      *     The value of the waveform at the given location.
      */
     var interpolateSample = function getValueAt(audioData, t) {
@@ -371,7 +371,7 @@ Guacamole.RawAudioRecorder = function RawAudioRecorder(stream, mimetype) {
      *     The Web Audio API AudioBuffer that should be converted to a raw
      *     audio packet.
      *
-     * @returns {SampleArray}
+     * @returns {!SampleArray}
      *     A new raw audio packet containing the audio data from the provided
      *     AudioBuffer.
      */
@@ -561,7 +561,7 @@ Guacamole.RawAudioRecorder.prototype = new Guacamole.AudioRecorder();
  * @param {String} mimetype
  *     The mimetype to check.
  *
- * @returns {Boolean}
+ * @returns {boolean}
  *     true if the given mimetype is supported by Guacamole.RawAudioRecorder,
  *     false otherwise.
  */
@@ -583,7 +583,7 @@ Guacamole.RawAudioRecorder.isSupportedType = function isSupportedType(mimetype)
  * additional parameters. Something like "audio/L8;rate=44100" would be valid,
  * however (see https://tools.ietf.org/html/rfc4856).
  *
- * @returns {String[]}
+ * @returns {string[]}
  *     A list of all mimetypes supported by Guacamole.RawAudioRecorder,
  *     excluding any parameters. If the necessary JavaScript APIs for recording
  *     raw audio are absent, this list will be empty.
diff --git a/guacamole-common-js/src/main/webapp/modules/BlobWriter.js b/guacamole-common-js/src/main/webapp/modules/BlobWriter.js
index bcb422aeb..08213fdce 100644
--- a/guacamole-common-js/src/main/webapp/modules/BlobWriter.js
+++ b/guacamole-common-js/src/main/webapp/modules/BlobWriter.js
@@ -67,7 +67,7 @@ Guacamole.BlobWriter = function BlobWriter(stream) {
      * @param {Number} end
      *     The ending offset of the slice, in bytes, exclusive.
      *
-     * @returns {Blob}
+     * @returns {!Blob}
      *     A Blob containing the data within the given Blob starting at
      *     <code>start</code> and ending at <code>end - 1</code>.
      */
diff --git a/guacamole-common-js/src/main/webapp/modules/Client.js b/guacamole-common-js/src/main/webapp/modules/Client.js
index 9ce54e329..7aee174c4 100644
--- a/guacamole-common-js/src/main/webapp/modules/Client.js
+++ b/guacamole-common-js/src/main/webapp/modules/Client.js
@@ -406,7 +406,7 @@ Guacamole.Client = function(tunnel) {
      * instruction which creates the stream, such as a "clipboard", "file", or
      * "pipe" instruction.
      *
-     * @returns {Guacamole.OutputStream}
+     * @returns {!Guacamole.OutputStream}
      *     A new Guacamole.OutputStream with a newly-allocated index and
      *     associated with this Guacamole.Client.
      */
@@ -430,7 +430,7 @@ Guacamole.Client = function(tunnel) {
      *     The mimetype of the audio data that will be sent along the returned
      *     stream.
      *
-     * @return {Guacamole.OutputStream}
+     * @return {!Guacamole.OutputStream}
      *     The created audio stream.
      */
     this.createAudioStream = function(mimetype) {
@@ -449,7 +449,7 @@ Guacamole.Client = function(tunnel) {
      *
      * @param {String} mimetype The mimetype of the file being sent.
      * @param {String} filename The filename of the file being sent.
-     * @return {Guacamole.OutputStream} The created file stream.
+     * @return {!Guacamole.OutputStream} The created file stream.
      */
     this.createFileStream = function(mimetype, filename) {
 
@@ -466,7 +466,7 @@ Guacamole.Client = function(tunnel) {
      *
      * @param {String} mimetype The mimetype of the data being sent.
      * @param {String} name The name of the pipe.
-     * @return {Guacamole.OutputStream} The created file stream.
+     * @return {!Guacamole.OutputStream} The created file stream.
      */
     this.createPipeStream = function(mimetype, name) {
 
@@ -483,7 +483,7 @@ Guacamole.Client = function(tunnel) {
      *
      * @param {String} mimetype The mimetype of the data being sent.
      * @param {String} name The name of the pipe.
-     * @return {Guacamole.OutputStream} The created file stream.
+     * @return {!Guacamole.OutputStream} The created file stream.
      */
     this.createClipboardStream = function(mimetype) {
 
@@ -535,7 +535,7 @@ Guacamole.Client = function(tunnel) {
      * @param {String} name
      *     The defined name of an output stream within the given object.
      *
-     * @returns {Guacamole.OutputStream}
+     * @returns {!Guacamole.OutputStream}
      *     An output stream which will write blobs to the named output stream
      *     of the given object.
      */
diff --git a/guacamole-common-js/src/main/webapp/modules/Display.js b/guacamole-common-js/src/main/webapp/modules/Display.js
index 41f04c7b3..31c22aaa5 100644
--- a/guacamole-common-js/src/main/webapp/modules/Display.js
+++ b/guacamole-common-js/src/main/webapp/modules/Display.js
@@ -194,7 +194,7 @@ Guacamole.Display = function() {
          * Returns whether this frame is ready to be rendered. This function
          * returns true if and only if ALL underlying tasks are unblocked.
          * 
-         * @returns {Boolean} true if all underlying tasks are unblocked,
+         * @returns {boolean} true if all underlying tasks are unblocked,
          *                    false otherwise.
          */
         this.isReady = function() {
@@ -282,7 +282,7 @@ Guacamole.Display = function() {
      * @private
      * @param {function} handler The function to call when possible, if any.
      * @param {boolean} blocked Whether the task should start blocked.
-     * @returns {Task} The Task created and added to the queue for future
+     * @returns {!Task} The Task created and added to the queue for future
      *                 running.
      */
     function scheduleTask(handler, blocked) {
@@ -294,7 +294,7 @@ Guacamole.Display = function() {
     /**
      * Returns the element which contains the Guacamole display.
      * 
-     * @return {Element} The element containing the Guacamole display.
+     * @return {!Element} The element containing the Guacamole display.
      */
     this.getElement = function() {
         return bounds;
@@ -324,7 +324,7 @@ Guacamole.Display = function() {
      * this layer, but the default layer cannot be removed and is the absolute
      * ancestor of all other layers.
      * 
-     * @return {Guacamole.Display.VisibleLayer} The default layer.
+     * @return {!Guacamole.Display.VisibleLayer} The default layer.
      */
     this.getDefaultLayer = function() {
         return default_layer;
@@ -335,7 +335,7 @@ Guacamole.Display = function() {
      * a layer for the image of the mouse cursor. This layer is a special case
      * and exists above all other layers, similar to the hardware mouse cursor.
      * 
-     * @return {Guacamole.Display.VisibleLayer} The cursor layer.
+     * @return {!Guacamole.Display.VisibleLayer} The cursor layer.
      */
     this.getCursorLayer = function() {
         return cursor;
@@ -346,7 +346,7 @@ Guacamole.Display = function() {
      * layer, but can be moved to be a child of any other layer. Layers returned
      * by this function are visible.
      * 
-     * @return {Guacamole.Display.VisibleLayer} The newly-created layer.
+     * @return {!Guacamole.Display.VisibleLayer} The newly-created layer.
      */
     this.createLayer = function() {
         var layer = new Guacamole.Display.VisibleLayer(displayWidth, displayHeight);
@@ -359,7 +359,7 @@ Guacamole.Display = function() {
      * are implemented in the same manner as layers, but do not provide the
      * same nesting semantics.
      * 
-     * @return {Guacamole.Layer} The newly-created buffer.
+     * @return {!Guacamole.Layer} The newly-created buffer.
      */
     this.createBuffer = function() {
         var buffer = new Guacamole.Layer(0, 0);
@@ -1202,7 +1202,7 @@ Guacamole.Display = function() {
      * Returns a canvas element containing the entire display, with all child
      * layers composited within.
      *
-     * @return {HTMLCanvasElement} A new canvas element containing a copy of
+     * @return {!HTMLCanvasElement} A new canvas element containing a copy of
      *                             the display.
      */
     this.flatten = function() {
@@ -1400,7 +1400,7 @@ Guacamole.Display.VisibleLayer = function(width, height) {
     /**
      * Returns the element containing the canvas and any other elements
      * associated with this layer.
-     * @returns {Element} The element containing this layer's canvas.
+     * @returns {!Element} The element containing this layer's canvas.
      */
     this.getElement = function() {
         return div;
diff --git a/guacamole-common-js/src/main/webapp/modules/JSONReader.js b/guacamole-common-js/src/main/webapp/modules/JSONReader.js
index 6d083b066..19b354df5 100644
--- a/guacamole-common-js/src/main/webapp/modules/JSONReader.js
+++ b/guacamole-common-js/src/main/webapp/modules/JSONReader.js
@@ -58,7 +58,7 @@ Guacamole.JSONReader = function guacamoleJSONReader(stream) {
     /**
      * Returns the current length of this Guacamole.JSONReader, in characters.
      *
-     * @return {Number}
+     * @return {!Number}
      *     The current length of this Guacamole.JSONReader.
      */
     this.getLength = function getLength() {
diff --git a/guacamole-common-js/src/main/webapp/modules/Keyboard.js b/guacamole-common-js/src/main/webapp/modules/Keyboard.js
index ead938f6d..c6b40eb7b 100644
--- a/guacamole-common-js/src/main/webapp/modules/Keyboard.js
+++ b/guacamole-common-js/src/main/webapp/modules/Keyboard.js
@@ -181,7 +181,7 @@ Guacamole.Keyboard = function Keyboard(element) {
          * Returns the number of milliseconds elapsed since this event was
          * received.
          *
-         * @return {Number} The number of milliseconds elapsed since this
+         * @return {!Number} The number of milliseconds elapsed since this
          *                  event was received.
          */
         this.getAge = function() {
@@ -693,7 +693,7 @@ Guacamole.Keyboard = function Keyboard(element) {
      * @param {Number} keysym
      *     The keysym to check.
      *
-     * @returns {Boolean}
+     * @returns {boolean}
      *     true if the given keysym corresponds to a printable character,
      *     false otherwise.
      */
@@ -778,7 +778,7 @@ Guacamole.Keyboard = function Keyboard(element) {
      * @param {String} keyIdentifier
      *     The legacy keyIdentifier from a browser keydown/keyup event.
      *
-     * @returns {Boolean}
+     * @returns {boolean}
      *     true if the keyIdentifier looks sane, false if the keyIdentifier
      *     appears incorrectly derived or is missing entirely.
      */
@@ -1046,7 +1046,7 @@ Guacamole.Keyboard = function Keyboard(element) {
      * inspection of other key events.
      *
      * @private
-     * @returns {Boolean}
+     * @returns {boolean}
      *     true if all currently pressed keys were implicitly pressed, false
      *     otherwise.
      */
@@ -1263,7 +1263,7 @@ Guacamole.Keyboard = function Keyboard(element) {
      * @param {Event} e
      *     The Event to mark.
      *
-     * @returns {Boolean}
+     * @returns {boolean}
      *     true if the given Event was successfully marked, false if the given
      *     Event was already marked.
      */
@@ -1487,7 +1487,7 @@ Guacamole.Keyboard.ModifierState = function() {
  * Returns the modifier state applicable to the keyboard event given.
  * 
  * @param {KeyboardEvent} e The keyboard event to read.
- * @returns {Guacamole.Keyboard.ModifierState} The current state of keyboard
+ * @returns {!Guacamole.Keyboard.ModifierState} The current state of keyboard
  *                                             modifiers.
  */
 Guacamole.Keyboard.ModifierState.fromKeyboardEvent = function(e) {
diff --git a/guacamole-common-js/src/main/webapp/modules/Layer.js b/guacamole-common-js/src/main/webapp/modules/Layer.js
index cd87d8d1d..9561be423 100644
--- a/guacamole-common-js/src/main/webapp/modules/Layer.js
+++ b/guacamole-common-js/src/main/webapp/modules/Layer.js
@@ -271,7 +271,7 @@ Guacamole.Layer = function(width, height) {
      * of the canvas may not exactly match those of the Layer, as resizing a
      * canvas while maintaining its state is an expensive operation.
      *
-     * @returns {HTMLCanvasElement}
+     * @returns {!HTMLCanvasElement}
      *     The canvas element backing this Layer.
      */
     this.getCanvas = function getCanvas() {
@@ -283,7 +283,7 @@ Guacamole.Layer = function(width, height) {
      * Unlike getCanvas(), the canvas element returned is guaranteed to have
      * the exact same dimensions as the Layer.
      *
-     * @returns {HTMLCanvasElement}
+     * @returns {!HTMLCanvasElement}
      *     A new canvas element containing a copy of the image content this
      *     Layer.
      */
diff --git a/guacamole-common-js/src/main/webapp/modules/Mouse.js b/guacamole-common-js/src/main/webapp/modules/Mouse.js
index b714ee69d..0156957e5 100644
--- a/guacamole-common-js/src/main/webapp/modules/Mouse.js
+++ b/guacamole-common-js/src/main/webapp/modules/Mouse.js
@@ -372,7 +372,7 @@ Guacamole.Mouse = function(element) {
      * @param {HTMLCanvasElement} canvas The cursor image.
      * @param {Number} x The X-coordinate of the cursor hotspot.
      * @param {Number} y The Y-coordinate of the cursor hotspot.
-     * @return {Boolean} true if the cursor was successfully set, false if the
+     * @return {!Boolean} true if the cursor was successfully set, false if the
      *                   cursor could not be set for any reason.
      */
     this.setCursor = function(canvas, x, y) {
@@ -947,7 +947,7 @@ Guacamole.Mouse.Touchscreen = function(element) {
      *
      * @private
      * @param {TouchEvent} e The touch event to check.
-     * @return {Boolean} true if the movement threshold is exceeded, false
+     * @return {!Boolean} true if the movement threshold is exceeded, false
      *                   otherwise.
      */
     function finger_moved(e) {
diff --git a/guacamole-common-js/src/main/webapp/modules/OnScreenKeyboard.js b/guacamole-common-js/src/main/webapp/modules/OnScreenKeyboard.js
index 69e98872e..d76e75933 100644
--- a/guacamole-common-js/src/main/webapp/modules/OnScreenKeyboard.js
+++ b/guacamole-common-js/src/main/webapp/modules/OnScreenKeyboard.js
@@ -217,7 +217,7 @@ Guacamole.OnScreenKeyboard = function(layout) {
      * @param {String[]} names
      *     The names of all modifiers to test.
      *
-     * @returns {Boolean}
+     * @returns {boolean}
      *     true if all specified modifiers are pressed, false otherwise.
      */
     var modifiersPressed = function modifiersPressed(names) {
@@ -428,7 +428,7 @@ Guacamole.OnScreenKeyboard = function(layout) {
 
     /**
      * Returns the element containing the entire on-screen keyboard.
-     * @returns {Element} The element containing the entire on-screen keyboard.
+     * @returns {!Element} The element containing the entire on-screen keyboard.
      */
     this.getElement = function() {
         return keyboard;
@@ -470,7 +470,7 @@ Guacamole.OnScreenKeyboard = function(layout) {
      *     which may be the title of the key (a string), the keysym (a number),
      *     a single Key object, or an array of Key objects.
      *     
-     * @returns {Guacamole.OnScreenKeyboard.Key[]}
+     * @returns {!Guacamole.OnScreenKeyboard.Key[]}
      *     An array of all keys associated with the given name.
      */
     var asKeyArray = function asKeyArray(name, object) {
@@ -554,7 +554,7 @@ Guacamole.OnScreenKeyboard = function(layout) {
      *     An arbitrary string representing the name of some component of the
      *     on-screen keyboard.
      *
-     * @returns {String}
+     * @returns {string}
      *     A string formatted for use as a CSS class name.
      */
     var getCSSName = function getCSSName(name) {
diff --git a/guacamole-common-js/src/main/webapp/modules/SessionRecording.js b/guacamole-common-js/src/main/webapp/modules/SessionRecording.js
index 87be39c2e..b30fe467b 100644
--- a/guacamole-common-js/src/main/webapp/modules/SessionRecording.js
+++ b/guacamole-common-js/src/main/webapp/modules/SessionRecording.js
@@ -215,7 +215,7 @@ Guacamole.SessionRecording = function SessionRecording(tunnel) {
      * @param {Number} timestamp
      *     The timestamp to convert to a relative timestamp.
      *
-     * @returns {Number}
+     * @returns {number}
      *     The difference in milliseconds between the given timestamp and the
      *     first frame of the recording, or zero if no frames yet exist.
      */
@@ -506,7 +506,7 @@ Guacamole.SessionRecording = function SessionRecording(tunnel) {
     /**
      * Returns whether playback is currently in progress.
      *
-     * @returns {Boolean}
+     * @returns {boolean}
      *     true if playback is currently in progress, false otherwise.
      */
     this.isPlaying = function isPlaying() {
diff --git a/guacamole-common-js/src/main/webapp/modules/Status.js b/guacamole-common-js/src/main/webapp/modules/Status.js
index 3acfd63c8..c831246fe 100644
--- a/guacamole-common-js/src/main/webapp/modules/Status.js
+++ b/guacamole-common-js/src/main/webapp/modules/Status.js
@@ -58,7 +58,7 @@ Guacamole.Status = function(code, message) {
 
     /**
      * Returns whether this status represents an error.
-     * @returns {Boolean} true if this status represents an error, false
+     * @returns {boolean} true if this status represents an error, false
      *                    otherwise.
      */
     this.isError = function() {
diff --git a/guacamole-common-js/src/main/webapp/modules/StringReader.js b/guacamole-common-js/src/main/webapp/modules/StringReader.js
index fa42503e1..fb3125327 100644
--- a/guacamole-common-js/src/main/webapp/modules/StringReader.js
+++ b/guacamole-common-js/src/main/webapp/modules/StringReader.js
@@ -65,7 +65,7 @@ Guacamole.StringReader = function(stream) {
      * 
      * @private
      * @param {ArrayBuffer} buffer Arbitrary UTF-8 data.
-     * @return {String} A decoded Unicode string.
+     * @return {string} A decoded Unicode string.
      */
     function __decode_utf8(buffer) {
 
diff --git a/guacamole-common-js/src/main/webapp/modules/Tunnel.js b/guacamole-common-js/src/main/webapp/modules/Tunnel.js
index 14642667b..49129888e 100644
--- a/guacamole-common-js/src/main/webapp/modules/Tunnel.js
+++ b/guacamole-common-js/src/main/webapp/modules/Tunnel.js
@@ -90,7 +90,7 @@ Guacamole.Tunnel = function() {
     /**
      * Returns whether this tunnel is currently connected.
      *
-     * @returns {Boolean}
+     * @returns {boolean}
      *     true if this tunnel is currently connected, false otherwise.
      */
     this.isConnected = function isConnected() {
@@ -412,7 +412,7 @@ Guacamole.HTTPTunnel = function(tunnelURL, crossDomain, extraTunnelHeaders) {
          * 
          * @private
          * @param value The value to convert.
-         * @return {String} The converted value. 
+         * @return {string} The converted value.
          */
         function getElement(value) {
             var string = new String(value);
@@ -934,7 +934,7 @@ Guacamole.WebSocketTunnel = function(tunnelURL) {
          * 
          * @private
          * @param value The value to convert.
-         * @return {String} The converted value. 
+         * @return {string} The converted value.
          */
         function getElement(value) {
             var string = new String(value);
diff --git a/guacamole-common-js/src/main/webapp/modules/VideoPlayer.js b/guacamole-common-js/src/main/webapp/modules/VideoPlayer.js
index 9581d51af..641e06eb3 100644
--- a/guacamole-common-js/src/main/webapp/modules/VideoPlayer.js
+++ b/guacamole-common-js/src/main/webapp/modules/VideoPlayer.js
@@ -50,7 +50,7 @@ Guacamole.VideoPlayer = function VideoPlayer() {
  * @param {String} mimetype
  *     The mimetype to check.
  *
- * @returns {Boolean}
+ * @returns {boolean}
  *     true if the given mimetype is supported by any built-in
  *     Guacamole.VideoPlayer, false otherwise.
  */
@@ -68,7 +68,7 @@ Guacamole.VideoPlayer.isSupportedType = function isSupportedType(mimetype) {
  * mimetypes themselves will be listed. Any mimetype parameters, even required
  * ones, will not be included in the list.
  *
- * @returns {String[]}
+ * @returns {string[]}
  *     A list of all mimetypes supported by any built-in Guacamole.VideoPlayer,
  *     excluding any parameters.
  */