Add symbol tags as proposed for LSP specification

See microsoft/language-server-protocol#2003

org.eclipse.lsp4j/src/main/java/org/eclipse/lsp4j/SymbolTag.java

@@ -14,15 +14,130 @@
 
 /**
  * Symbol tags are extra annotations that tweak the rendering of a symbol.
- * <p>
- * Since 3.16
+ * Since 3.18
  */
 public enum SymbolTag {
 
 	/**
 	 * Render a symbol as obsolete, usually using a strike-out.
+	 * Since 3.16
 	 */
-	Deprecated(1);
+	Deprecated(1),
+
+	/**
+	 * Render a symbol with visibility / access modifier "private".
+	 * @since 3.18
+	 */
+	Private(2),
+
+	/**
+	 * Render a symbol with visibility "package private", e.g. in Java.
+	 * @since 3.18
+	 */
+	Package(3),
+
+	/**
+	 * Render a symbol with visibility / access modifier "protected".
+	 * The modifier could be combined e.g. with "internal" or "private" in languages like C#.
+	 * @since 3.18
+	 */
+	Protected(4),
+
+	/**
+	 * Render a symbol with visibility / access modifier "public".
+	 * @since 3.18
+	 */
+	Public(5),
+
+	/**
+	 * Render a symbol with visibility / access modifier "internal", e.g. in C# or Kotlin.
+	 * @since 3.18
+	 */
+	Internal(6),
+
+	/**
+	 * Render a symbol with visibility / access modifier "file", e.g. in C#.
+	 * @since 3.18
+	 */
+	File(7),
+
+	/**
+	 * Render a symbol as "static".
+	 * @since 3.18
+	 */
+	Static(8),
+
+	/**
+	 * Render a symbol as "abstract".
+	 * @since 3.18
+	 */
+	Abstract(9),
+
+	/**
+	 * Render a symbol as "final".
+	 * @since 3.18
+	 */
+	Final(10),
+
+	/**
+	 * Render a symbol as "sealed", e.g. classes and interfaces in Kotlin.
+	 * @since 3.18
+	 */
+	Sealed(11),
+
+	/**
+	 * Render a symbol as "transient", e.g. in Java.
+	 * @since 3.18
+	 */
+	Transient(12),
+
+	/**
+	 * Render a symbol as "volatile", e.g. in Java.
+	 * @since 3.18
+	 */
+	Volatile(13),
+
+	/**
+	 * Render a symbol as "synchronized", e.g. in Java.
+	 * @since 3.18
+	 */
+	Synchronized(14),
+
+	/**
+	 * Render a symbol as "virtual", e.g. in C++.
+	 * @since 3.18
+	 */
+	Virtual(15),
+
+	/**
+	 * Render a symbol as "nullable", e.g. types with '?' in Kotlin.
+	 * @since 3.18
+	 */
+	Nullable(16),
+
+	/**
+	 * Render a symbol as "never null", e.g. types without '?' in Kotlin.
+	 * @since 3.18
+	 */
+	NonNull(17),
+
+	/**
+	 * Render a symbol as declaration.
+	 * @since 3.18
+	 */
+	Declaration(18),
+
+	/**
+	 * Render a symbol as definition (in contrast to declaration), e.g. in header files in C++.
+	 * @since 3.18
+	 */
+	Definition(19),
+
+	/**
+	 * Render a symbol as "read-only", i.e. variables / properties that cannot be changed.
+	 * @since 3.18
+	 */
+	ReadOnly(20);
 
 	private final int value;