Java build error "returns unavailable type"

Question

I am in confusion related to this build issue. Following cases are build successfully.

case 1

`

public Insets getOpticalInsets() {
 System.out.println(" hello ");
 return Insets.NONE;
}

`

case 2

`

public Insets getOpticalInsets() { 
{
 return Insets.NONE;
}
}

`

but the following case fails and gives the error message as " returns unavailable type Insets"

failed case

`

public Insets getOpticalInsets() { 
{
 System.out.println(" hello ");
 return Insets.NONE;
}
}

`

I have searched about similar errors but could not find anything useful. Can somebody explain me what is actually the error.

Complete Log message

frameworks/base/graphics/java/android/graphics/drawable/Drawable.java:601: error 110: Method android.graphics.drawable.Drawable.getOpticalInsets returns unavailable type Insets

Source file:

`

package android.graphics.drawable;

import android.graphics.Insets;
import android.os.Trace;
import org.xmlpull.v1.XmlPullParser;
import org.xmlpull.v1.XmlPullParserException;

import android.content.res.Resources;
import android.content.res.TypedArray;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.ColorFilter;
import android.graphics.NinePatch;
import android.graphics.PixelFormat;
import android.graphics.PorterDuff;
import android.graphics.PorterDuffColorFilter;
import android.graphics.Rect;
import android.graphics.Region;
import android.os.Build;
import android.util.AttributeSet;
import android.util.DisplayMetrics;
import android.util.StateSet;
import android.util.TypedValue;
import android.util.Xml;

import java.io.IOException;
import java.io.InputStream;
import java.lang.ref.WeakReference;
import java.util.Arrays;


public abstract class Drawable {
    private static final Rect ZERO_BOUNDS_RECT = new Rect();

    private int[] mStateSet = StateSet.WILD_CARD;
    private int mLevel = 0;
    private int mChangingConfigurations = 0;
    private Rect mBounds = ZERO_BOUNDS_RECT;  
    private WeakReference<Callback> mCallback = null;
    private boolean mVisible = true;

    private int mLayoutDirection;


    private String mImagePath;



    public Insets getOpticalInsets() {        
            {
                System.out.println(" hello ");
                return Insets.NONE;
            }
    }



}

`