fix wrong auto-detection of country by language

When locale contains only language, but not country, the phone generator tries to guess the country.

For few specific languages, the guess was wrong. It happened for languages which code occasionally matches some other country's code.

```
new Faker(new Language("am").phoneNumber(); // generated Armenian phone instead of Ethiopian

new Faker(new Language("ar").phoneNumber(); // generated Argentina phone instead of Saudi Arabia
```

etc.

Inspired by #1788

Author: asolntsev

src/main/java/net/datafaker/providers/base/PhoneNumber.java

@@ -80,29 +80,48 @@ private static String countryCodeIso2(Locale locale) {
     /**
      * A hack to detect country when only a language is given.
      * <p>
-     *     It's not correct because most languages are used in multiple countries.
-     *     If users need to generate random phone number, they should create locale with country,
-     *     e.g. {@code new Locale("ta_IN")}, and not just {@code new Locale("ta")}.
+     * It's not correct because most languages are used in multiple countries.
+     * If users need to generate random phone number, they should create locale with country,
+     * e.g. {@code new Locale("ta_IN")}, and not just {@code new Locale("ta")}.
      * </p>
      * <p>
-     *     We keep this mapping here just for backward compatibility.
+     * We keep this mapping here just for backward compatibility.
      * </p>
      */
     private static String detectCountryByLanguage(String language) {
         return switch (language) {
+            case "af" -> "ZA"; // Afrikaans language -> South Africa
+            case "ar" -> "SA"; // Arabic language -> Saudi Arabia (SA)
+            case "am" -> "ET"; // Amharic language -> Ethiopia (ET)
+            case "be" -> "BY"; // Belarus
+            case "bn" -> "BD"; // Bengali language -> Bangladesh (BD)
+            case "bs" -> "BA"; // Bosnian language -> Bosnia & Herzegovina (BA)
+            case "ca" -> "ES"; // Catalan language -> Spain (ES)
+            case "cy" -> "GB"; // Welsh language -> United Kingdom (GB)
+            case "cs" -> "CZ"; // Czech Republic
+            case "el" -> "GR"; // Greece
+            case "et" -> "EE"; // Estonian language -> Estonia (EE)
             case "en" -> "US"; // it has been used by default for English
-            case "test" -> "US"; // What the hell is "test" language?
+            case "eu" -> "ES"; // Basque (Basque Country | Spain)
+            case "fa" -> "IR"; // Persian language (Farsi) -> Iran (IR)
+            case "ga" -> "IE"; // Irish/Gaelic language -> Ireland (IE)
+            case "gl" -> "ES"; // Galician (Spain)
+            case "he" -> "IL"; // Israel
+            case "hi" -> "IN"; // Hindi language -> India
             case "hy" -> "AM"; // Armenia
-            case "uk" -> "UA"; // Ukraine
             case "ja" -> "JP"; // Japan
-            case "fa" -> "IR"; // Iran
             case "ka" -> "GE"; // Georgia
-            case "sq" -> "AL"; // Albania
-            case "cs" -> "CZ"; // Czech Republic
-            case "be" -> "BY"; // Belarus
+            case "km" -> "KH"; // Khmer language -> Cambodia (KH)
             case "ko" -> "KR"; // Korea
-            case "he" -> "IL"; // Israel
+            case "mo" -> "MD"; // Moldavian language -> Moldova
+            case "sq" -> "AL"; // Albania
+            case "sw" -> "TZ"; // Swahili language -> Tanzania (TZ)
+            case "ug" -> "CN"; // Uyghur language -> China (CN)
+            case "ur" -> "PK"; // Urdu language -> Pakistan (PK)
             case "ta" -> "IN"; // Tamil language -> India (though, Tamil is used in multiple countries)
+            case "test" -> "US"; // What the hell is "test" language?
+            case "uk" -> "UA"; // Ukraine
+            case "zh" -> "CN"; // Chinese language -> China (CN)
             default -> language.toUpperCase(ROOT);
         };
     }

src/test/java/net/datafaker/providers/base/PhoneNumberValidityFinderTest.java

@@ -9,6 +9,7 @@
 import org.junit.jupiter.api.TestInstance;
 import org.junit.jupiter.params.ParameterizedTest;
 import org.junit.jupiter.params.provider.Arguments;
+import org.junit.jupiter.params.provider.CsvSource;
 import org.junit.jupiter.params.provider.MethodSource;
 
 import java.util.Locale;
@@ -53,6 +54,41 @@ void testLanguageOnlyPersianLocaleUsesIran() {
         assertThat(localFaker.phoneNumber().countryCodeIso2()).isEqualTo("IR");
     }
 
+    @ParameterizedTest
+    @CsvSource({
+        "en, US",
+        "hy, AM", // Armenian
+        "uk, UA", // Ukranian
+        "ja, JP", // Japanese
+        "fa, IR", // fa=Persian (Farsi) primarly used in Iran
+        "ka, GE", // Georgian
+        "sq, AL", // Albanian
+        "cs, CZ", // Czech
+        "be, BY", // Belarusian
+        "he, IL", // he = Hebrew - a Semitic language used by the ancient Hebrews and in modern Israel
+        "ta, IN", // Tamil
+        "et, EE", // Estonian
+        "el, GR", // Greek         → Greece  (el ≠ gr)
+        "eu, ES", // Basque        → Spain   (eu ≠ es; Basque Country)
+        "ca, ES", // Catalan       → Spain   (ca is also Canada's TLD, but lang→ES)
+        "cy, GB", // Welsh         → United Kingdom
+        "ga, IE", // Irish/Gaelic  → Ireland
+        "is, IS", // Icelandic     → Iceland  (happens to match here — keep for completeness)
+        "bs, BA", // Bosnian       → Bosnia & Herzegovina
+        "ar, SA", // Arabic        → Saudi Arabia (ar ≠ sa; Arabic used across 20+ countries)
+        "hi, IN", // Hindi         → India   (hi ≠ in)
+        "zh, CN", // Chinese       → China   (zh ≠ cn)
+        "am, ET", // Amharic       → Ethiopia (am ≠ et; am is Armenia's country code!)
+        "sw, TZ", // Swahili       → Tanzania (sw ≠ tz; also widely used in KE, UG)
+        "af, ZA", // Afrikaans     → South Africa (af ≠ za; af is Afghanistan's code!)
+
+    })
+    void detectsCountryByLanguage(String language, String expectedCountry) {
+        BaseFaker localFaker = new BaseFaker(new Locale(language));
+
+        assertThat(localFaker.phoneNumber().countryCodeIso2()).isEqualTo(expectedCountry);
+    }
+
     @ParameterizedTest
     @MethodSource("allSupportedLocales")
     void testAllPhoneNumbers(Locale supportedLocale) throws NumberParseException {