--- old/src/java.compiler/share/classes/javax/lang/model/SourceVersion.java	2019-03-25 08:53:35.544735632 -0700
+++ new/src/java.compiler/share/classes/javax/lang/model/SourceVersion.java	2019-03-25 08:53:35.220573632 -0700
@@ -58,7 +58,7 @@
      *   9: modules, small cleanups to 1.7 and 1.8 changes
      *  10: local-variable type inference (var)
      *  11: local-variable syntax for lambda parameters
-     *  12: TBD
+     *  12: no changes (switch expressions in preview)
      *  13: TBD
      */
 
@@ -208,38 +208,36 @@
 
     private static final SourceVersion latestSupported = getLatestSupported();
 
+    /*
+     * The integer to release enum constant implemented by this method
+     * assumes the JEP 322: "Time-Based Release Versioning" scheme is
+     * in effect. This scheme began in JDK 10. If the JDK versioning
+     * scheme is revised, this method may need to be updated
+     * accordingly.
+     */
     private static SourceVersion getLatestSupported() {
-        try {
-            String specVersion = System.getProperty("java.specification.version");
-
-            switch (specVersion) {
-                case "13":
-                    return RELEASE_13;
-                case "12":
-                    return RELEASE_12;
-                case "11":
-                    return RELEASE_11;
-                case "10":
-                    return RELEASE_10;
-                case "9":
-                    return RELEASE_9;
-                case "1.8":
-                    return RELEASE_8;
-                case "1.7":
-                    return RELEASE_7;
-                case "1.6":
-                    return RELEASE_6;
-            }
-        } catch (SecurityException se) {}
-
-        return RELEASE_5;
+        int intVersion = Runtime.version().feature();
+        return (intVersion >= 11) ?
+            valueOf("RELEASE_" + Math.min(13, intVersion)):
+            RELEASE_10;
     }
 
     /**
      * Returns the latest source version fully supported by the
-     * current execution environment.  {@code RELEASE_5} or later must
+     * current execution environment.  {@code RELEASE_9} or later must
      * be returned.
      *
+     * @apiNote This method is included alongside {@link latest} to
+     * allow situations where the language model API is running on a
+     * platform version different than the latest version modeled by
+     * the API to be identified. One way that sort of situation can
+     * occur is if a IDE or similar tool is using the API to model
+     * source version <i>N</i> while running on platform version
+     * (<i>N</i>&nbsp;-&nbsp;1). Running in this configuration is
+     * supported by the API. Running an API on platform versions
+     * earlier than (<i>N</i>&nbsp;-&nbsp;1) or later than <i>N</i>
+     * may or may not work as an implementation detail.
+     *
      * @return the latest source version that is fully supported
      */
     public static SourceVersion latestSupported() {