Fix KeyPath visibility

Fixes #728
diff --git a/lottie/src/main/java/com/airbnb/lottie/model/CubicCurveData.java b/lottie/src/main/java/com/airbnb/lottie/model/CubicCurveData.java
index 7751db8..82d3e5a 100644
--- a/lottie/src/main/java/com/airbnb/lottie/model/CubicCurveData.java
+++ b/lottie/src/main/java/com/airbnb/lottie/model/CubicCurveData.java
@@ -1,7 +1,11 @@
 package com.airbnb.lottie.model;
 
 import android.graphics.PointF;
+import android.support.annotation.RestrictTo;
 
+import static android.support.annotation.RestrictTo.Scope.LIBRARY;
+
+@RestrictTo(LIBRARY)
 public class CubicCurveData {
   private final PointF controlPoint1;
   private final PointF controlPoint2;
diff --git a/lottie/src/main/java/com/airbnb/lottie/model/DocumentData.java b/lottie/src/main/java/com/airbnb/lottie/model/DocumentData.java
index 72967d0..9064fd8 100644
--- a/lottie/src/main/java/com/airbnb/lottie/model/DocumentData.java
+++ b/lottie/src/main/java/com/airbnb/lottie/model/DocumentData.java
@@ -1,7 +1,11 @@
 package com.airbnb.lottie.model;
 
 import android.support.annotation.ColorInt;
+import android.support.annotation.RestrictTo;
 
+import static android.support.annotation.RestrictTo.Scope.LIBRARY;
+
+@RestrictTo(LIBRARY)
 public class DocumentData {
 
   public final String text;
diff --git a/lottie/src/main/java/com/airbnb/lottie/model/Font.java b/lottie/src/main/java/com/airbnb/lottie/model/Font.java
index d4beb6c..f5f59cf 100644
--- a/lottie/src/main/java/com/airbnb/lottie/model/Font.java
+++ b/lottie/src/main/java/com/airbnb/lottie/model/Font.java
@@ -1,5 +1,10 @@
 package com.airbnb.lottie.model;
 
+import android.support.annotation.RestrictTo;
+
+import static android.support.annotation.RestrictTo.Scope.LIBRARY;
+
+@RestrictTo(LIBRARY)
 public class Font {
 
   private final String family;
diff --git a/lottie/src/main/java/com/airbnb/lottie/model/FontCharacter.java b/lottie/src/main/java/com/airbnb/lottie/model/FontCharacter.java
index ec9a730..29044d8 100644
--- a/lottie/src/main/java/com/airbnb/lottie/model/FontCharacter.java
+++ b/lottie/src/main/java/com/airbnb/lottie/model/FontCharacter.java
@@ -1,9 +1,14 @@
 package com.airbnb.lottie.model;
 
+import android.support.annotation.RestrictTo;
+
 import com.airbnb.lottie.model.content.ShapeGroup;
 
 import java.util.List;
 
+import static android.support.annotation.RestrictTo.Scope.LIBRARY;
+
+@RestrictTo(LIBRARY)
 public class FontCharacter {
 
   public static int hashFor(char character, String fontFamily, String style) {
diff --git a/lottie/src/main/java/com/airbnb/lottie/model/KeyPathElement.java b/lottie/src/main/java/com/airbnb/lottie/model/KeyPathElement.java
index 42640c8..df0f703 100644
--- a/lottie/src/main/java/com/airbnb/lottie/model/KeyPathElement.java
+++ b/lottie/src/main/java/com/airbnb/lottie/model/KeyPathElement.java
@@ -1,14 +1,18 @@
 package com.airbnb.lottie.model;
 
 import android.support.annotation.Nullable;
+import android.support.annotation.RestrictTo;
 
 import com.airbnb.lottie.value.LottieValueCallback;
 
 import java.util.List;
 
+import static android.support.annotation.RestrictTo.Scope.LIBRARY;
+
 /**
  * Any item that can be a part of a {@link KeyPath} should implement this.
  */
+@RestrictTo(LIBRARY)
 public interface KeyPathElement {
 
   /**
diff --git a/lottie/src/main/java/com/airbnb/lottie/model/MutablePair.java b/lottie/src/main/java/com/airbnb/lottie/model/MutablePair.java
index 2ab3dfd..f45c425 100644
--- a/lottie/src/main/java/com/airbnb/lottie/model/MutablePair.java
+++ b/lottie/src/main/java/com/airbnb/lottie/model/MutablePair.java
@@ -1,12 +1,16 @@
 package com.airbnb.lottie.model;
 
 import android.support.annotation.Nullable;
+import android.support.annotation.RestrictTo;
 import android.support.v4.util.Pair;
 
+import static android.support.annotation.RestrictTo.Scope.LIBRARY;
+
 /**
  * Non final version of {@link Pair}
  * @param <T>
  */
+@RestrictTo(LIBRARY)
 public class MutablePair<T> {
   @Nullable T first;
   @Nullable T second;
diff --git a/lottie/src/main/java/com/airbnb/lottie/model/package-info.java b/lottie/src/main/java/com/airbnb/lottie/model/package-info.java
deleted file mode 100644
index 54792cd..0000000
--- a/lottie/src/main/java/com/airbnb/lottie/model/package-info.java
+++ /dev/null
@@ -1,6 +0,0 @@
-@RestrictTo(LIBRARY)
-package com.airbnb.lottie.model;
-
-import android.support.annotation.RestrictTo;
-
-import static android.support.annotation.RestrictTo.Scope.LIBRARY;
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