Resolve nullable warnings for API 31 migration

Author: irfano

aztec/src/main/kotlin/org/wordpress/aztec/source/CssStyleFormatter.kt

@@ -1,11 +1,11 @@
 package org.wordpress.aztec.source
 
-import androidx.core.text.TextDirectionHeuristicsCompat
 import android.text.Editable
 import android.text.Layout
 import android.text.Spannable
 import android.text.style.BackgroundColorSpan
 import android.text.style.ForegroundColorSpan
+import androidx.core.text.TextDirectionHeuristicsCompat
 import org.wordpress.aztec.AztecAttributes
 import org.wordpress.aztec.spans.IAztecAlignmentSpan
 import org.wordpress.aztec.spans.IAztecAttributedSpan
@@ -121,7 +121,7 @@ class CssStyleFormatter {
 
             var styleAttributeValue = ""
             if (m.find()) {
-                styleAttributeValue = m.group(1)
+                m.group(1)?.let { styleAttributeValue = it }
             }
             return styleAttributeValue
         }

aztec/src/main/kotlin/org/wordpress/aztec/util/InstanceStateUtils.kt

@@ -2,7 +2,6 @@ package org.wordpress.aztec.util
 
 import android.content.Context
 import android.os.Bundle
-import android.text.TextUtils
 import org.wordpress.android.util.AppLog
 import java.io.File
 import java.io.FileInputStream
@@ -50,7 +49,7 @@ class InstanceStateUtils {
             // the full path is kept in the bundle so, get it from there
             val filename = bundle.getString(cacheFilenameKey(varName))
 
-            if (TextUtils.isEmpty(filename)) {
+            if (filename.isNullOrEmpty()) {
                 return defaultValue
             }
 

aztec/src/main/kotlin/org/wordpress/aztec/watchers/DeleteMediaElementWatcherAPI25AndHigher.kt

@@ -39,7 +39,7 @@ class DeleteMediaElementWatcherAPI25AndHigher(aztecText: AztecText) : TextWatche
             // real user deletions.
             aztecTextRef.get()?.postDelayed({
                 while (!queueHasBeenPopulatedInThisTimeframe && deletedSpans.isNotEmpty()) {
-                    deletedSpans.poll().onMediaDeleted()
+                    deletedSpans.poll()?.onMediaDeleted()
                 }
                 queueHasBeenPopulatedInThisTimeframe = false
             }, 500)