Convert StringUtils to Kotlin

.editorconfig

@@ -7,6 +7,10 @@ trim_trailing_whitespace = true
 max_line_length = 120
 indent_style = tab
 
+[*.kt]
+indent_style = space
+indent_size = 4
+
 [*.xml]
 indent_style = space
 indent_size = 2

.idea/codeStyles/Project.xml

@@ -36,6 +36,9 @@
       <option name="JD_ADD_BLANK_AFTER_DESCRIPTION" value="false" />
       <option name="JD_INDENT_ON_CONTINUATION" value="true" />
     </JavaCodeStyleSettings>
+    <JetCodeStyleSettings>
+      <option name="CODE_STYLE_DEFAULTS" value="KOTLIN_OFFICIAL" />
+    </JetCodeStyleSettings>
     <XML>
       <option name="XML_ATTRIBUTE_WRAP" value="0" />
       <option name="XML_ALIGN_ATTRIBUTES" value="false" />
@@ -75,5 +78,8 @@
         <option name="TAB_SIZE" value="2" />
       </indentOptions>
     </codeStyleSettings>
+    <codeStyleSettings language="kotlin">
+      <option name="CODE_STYLE_DEFAULTS" value="KOTLIN_OFFICIAL" />
+    </codeStyleSettings>
   </code_scheme>
 </component>

util/pom.xml

@@ -23,6 +23,10 @@
       <groupId>org.slf4j</groupId>
       <artifactId>slf4j-api</artifactId>
     </dependency>
+    <dependency>
+      <groupId>org.jetbrains.kotlin</groupId>
+      <artifactId>kotlin-stdlib-jdk8</artifactId>
+    </dependency>
     <dependency>
       <groupId>org.junit.jupiter</groupId>
       <artifactId>junit-jupiter</artifactId>

util/src/main/java/dev/openrs2/util/StringUtils.java

@@ -1,29 +0,0 @@
-package dev.openrs2.util;
-
-import com.google.common.base.Preconditions;
-
-public final class StringUtils {
-	public static String indefiniteArticle(String str) {
-		Preconditions.checkArgument(!str.isEmpty());
-
-		var first = Character.toLowerCase(str.charAt(0));
-		if (first == 'a' || first == 'e' || first == 'i' || first == 'o' || first == 'u') {
-			return "an";
-		} else {
-			return "a";
-		}
-	}
-
-	public static String capitalize(String str) {
-		if (str.isEmpty()) {
-			return str;
-		}
-
-		var first = Character.toUpperCase(str.charAt(0));
-		return first + str.substring(1);
-	}
-
-	private StringUtils() {
-		/* empty */
-	}
-}

util/src/main/java/dev/openrs2/util/StringUtils.kt

@@ -0,0 +1,20 @@
+package dev.openrs2.util
+
+object StringUtils {
+    // TODO(gpe): convert to an extension function
+    @JvmStatic
+    fun indefiniteArticle(str: String): String {
+        require(str.isNotEmpty())
+
+        val first = str.first().toLowerCase()
+        return when (first) {
+            'a', 'e', 'i', 'o', 'u' -> "an"
+            else -> "a"
+        }
+    }
+
+    @JvmStatic
+    fun capitalize(str: String): String {
+        return str.capitalize()
+    }
+}