diff -r 4ebc2e2fb97c -r 71c04702a3d5 src/jdk.compiler/share/classes/com/sun/tools/sjavac/Util.java
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/jdk.compiler/share/classes/com/sun/tools/sjavac/Util.java	Tue Sep 12 19:03:39 2017 +0200
@@ -0,0 +1,247 @@
+/*
+ * Copyright (c) 2012, 2016, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.  Oracle designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Oracle in the LICENSE file that accompanied this code.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+package com.sun.tools.sjavac;
+
+import java.io.File;
+import java.io.PrintWriter;
+import java.io.StringWriter;
+import java.nio.file.Path;
+import java.util.Arrays;
+import java.util.Collection;
+import java.util.HashSet;
+import java.util.Map;
+import java.util.Set;
+import java.util.StringTokenizer;
+import java.util.function.Function;
+import java.util.regex.Pattern;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
+
+/**
+ * Utilities.
+ *
+ *  <p><b>This is NOT part of any supported API.
+ *  If you write code that depends on this, you do so at your own risk.
+ *  This code and its internal interfaces are subject to change or
+ *  deletion without notice.</b>
+ */
+public class Util {
+
+    public static String toFileSystemPath(String pkgId) {
+        if (pkgId == null || pkgId.length()==0) return null;
+        String pn;
+        if (pkgId.charAt(0) == ':') {
+            // When the module is the default empty module.
+            // Do not prepend the module directory, because there is none.
+            // Thus :java.foo.bar translates to java/foo/bar (or \)
+            pn = pkgId.substring(1).replace('.',File.separatorChar);
+        } else {
+            // There is a module. Thus jdk.base:java.foo.bar translates
+            // into jdk.base/java/foo/bar
+            int cp = pkgId.indexOf(':');
+            String mn = pkgId.substring(0,cp);
+            pn = mn+File.separatorChar+pkgId.substring(cp+1).replace('.',File.separatorChar);
+        }
+        return pn;
+    }
+
+    public static String justPackageName(String pkgName) {
+        int c = pkgName.indexOf(":");
+        if (c == -1)
+            throw new IllegalArgumentException("Expected ':' in package name (" + pkgName + ")");
+        return pkgName.substring(c+1);
+    }
+
+    public static String extractStringOption(String opName, String s) {
+        return extractStringOption(opName, s, null);
+    }
+
+    public static String extractStringOption(String opName, String s, String deflt) {
+        int p = s.indexOf(opName+"=");
+        if (p == -1) return deflt;
+        p+=opName.length()+1;
+        int pe = s.indexOf(',', p);
+        if (pe == -1) pe = s.length();
+        return s.substring(p, pe);
+    }
+
+    public static boolean extractBooleanOption(String opName, String s, boolean deflt) {
+        String str = extractStringOption(opName, s);
+        return "true".equals(str) ? true
+             : "false".equals(str) ? false
+             : deflt;
+    }
+
+    public static int extractIntOption(String opName, String s) {
+        return extractIntOption(opName, s, 0);
+    }
+
+    public static int extractIntOption(String opName, String s, int deflt) {
+        int p = s.indexOf(opName+"=");
+        if (p == -1) return deflt;
+        p+=opName.length()+1;
+        int pe = s.indexOf(',', p);
+        if (pe == -1) pe = s.length();
+        int v = 0;
+        try {
+            v = Integer.parseInt(s.substring(p, pe));
+        } catch (Exception e) {}
+        return v;
+    }
+
+    /**
+     * Extract the package name from a fully qualified class name.
+     *
+     * Example: Given "pkg.subpkg.A" this method returns ":pkg.subpkg".
+     * Given "C" this method returns ":".
+     *
+     * @returns package name of the given class name
+     */
+    public static String pkgNameOfClassName(String fqClassName) {
+        int i = fqClassName.lastIndexOf('.');
+        String pkg = i == -1 ? "" : fqClassName.substring(0, i);
+        return ":" + pkg;
+    }
+
+    /**
+     * Clean out unwanted sub options supplied inside a primary option.
+     * For example to only had portfile remaining from:
+     *    settings="--server:id=foo,portfile=bar"
+     * do settings = cleanOptions("--server:",Util.set("-portfile"),settings);
+     *    now settings equals "--server:portfile=bar"
+     *
+     * @param allowedSubOptions A set of the allowed sub options, id portfile etc.
+     * @param s The option settings string.
+     */
+    public static String cleanSubOptions(Set<String> allowedSubOptions, String s) {
+        StringBuilder sb = new StringBuilder();
+        StringTokenizer st = new StringTokenizer(s, ",");
+        while (st.hasMoreTokens()) {
+            String o = st.nextToken();
+            int p = o.indexOf('=');
+            if (p>0) {
+                String key = o.substring(0,p);
+                String val = o.substring(p+1);
+                if (allowedSubOptions.contains(key)) {
+                    if (sb.length() > 0) sb.append(',');
+                    sb.append(key+"="+val);
+                }
+            }
+        }
+        return sb.toString();
+    }
+
+    /**
+     * Convenience method to create a set with strings.
+     */
+    public static Set<String> set(String... ss) {
+        Set<String> set = new HashSet<>();
+        set.addAll(Arrays.asList(ss));
+        return set;
+    }
+
+    /**
+     * Normalize windows drive letter paths to upper case to enable string
+     * comparison.
+     *
+     * @param file File name to normalize
+     * @return The normalized string if file has a drive letter at the beginning,
+     *         otherwise the original string.
+     */
+    public static String normalizeDriveLetter(String file) {
+        if (file.length() > 2 && file.charAt(1) == ':') {
+            return Character.toUpperCase(file.charAt(0)) + file.substring(1);
+        } else if (file.length() > 3 && file.charAt(0) == '*'
+                   && file.charAt(2) == ':') {
+            // Handle a wildcard * at the beginning of the string.
+            return file.substring(0, 1) + Character.toUpperCase(file.charAt(1))
+                   + file.substring(2);
+        }
+        return file;
+    }
+
+    /**
+     * Locate the setting for the server properties.
+     */
+    public static String findServerSettings(String[] args) {
+        for (String s : args) {
+            if (s.startsWith("--server:")) {
+                return s;
+            }
+        }
+        return null;
+    }
+
+    public static <E> Set<E> union(Set<? extends E> s1,
+                                   Set<? extends E> s2) {
+        Set<E> union = new HashSet<>();
+        union.addAll(s1);
+        union.addAll(s2);
+        return union;
+    }
+
+    public static <E> Set<E> subtract(Set<? extends E> orig,
+                                      Set<? extends E> toSubtract) {
+        Set<E> difference = new HashSet<>(orig);
+        difference.removeAll(toSubtract);
+        return difference;
+    }
+
+    public static String getStackTrace(Throwable t) {
+        StringWriter sw = new StringWriter();
+        t.printStackTrace(new PrintWriter(sw));
+        return sw.toString();
+    }
+
+    // TODO: Remove when refactoring from java.io.File to java.nio.file.Path.
+    public static File pathToFile(Path path) {
+        return path == null ? null : path.toFile();
+    }
+
+    public static <E> Set<E> intersection(Collection<? extends E> c1,
+                                          Collection<? extends E> c2) {
+        Set<E> intersection = new HashSet<E>(c1);
+        intersection.retainAll(c2);
+        return intersection;
+    }
+
+    public static <I, T> Map<I, T> indexBy(Collection<? extends T> c,
+                                           Function<? super T, ? extends I> indexFunction) {
+        return c.stream().collect(Collectors.<T, I, T>toMap(indexFunction, o -> o));
+    }
+
+    public static String fileSuffix(Path file) {
+        String fileNameStr = file.getFileName().toString();
+        int dotIndex = fileNameStr.indexOf('.');
+        return dotIndex == -1 ? "" : fileNameStr.substring(dotIndex);
+    }
+
+    public static Stream<String> getLines(String str) {
+        return str.isEmpty()
+                ? Stream.empty()
+                : Stream.of(str.split(Pattern.quote(System.lineSeparator())));
+    }
+}