[android] - replace platform default implementation using nunicode for uppercasing an lowercasing with an Android specific String.java equivalent

platform/android/MapboxGLAndroidSDK/src/main/java/com/mapbox/mapboxsdk/utils/StringUtils.java

@@ -0,0 +1,27 @@
+package com.mapbox.mapboxsdk.utils;
+
+import android.support.annotation.Keep;
+import android.support.annotation.NonNull;
+
+import java.text.Normalizer;
+
+/**
+ * String utility class used by core from jni.
+ */
+@Keep
+class StringUtils {
+
+  /**
+   * Normalises String input and strip diacritics from it.
+   *
+   * @return normalised String with stripped diacritics.
+   */
+  @Keep
+  @NonNull
+  static String unaccent(@NonNull String value) {
+    return Normalizer.normalize(value, Normalizer.Form.NFD)
+      .replaceAll("(\\p{InCombiningDiacriticalMarks}"
+        + "|\\p{InCombiningDiacriticalMarksForSymbols}"
+        + "|\\p{InCombiningDiacriticalMarksSupplement})+", "");
+  }
+}