ZOOKEEPER-3733: Fix issues reported in 3.6.0rc3

- metrics library LICENSE file has wrong file name
- spotbugs is not passing when '-SNAPSHOT' suffix is removed because the Info.java interface sets a null value for "qualifier"
- the name of the directory inside the source tarbal is not consistent with the file name and with 3.5 tradition

Author: Enrico Olivelli <eolivelli@apache.org>

Reviewers: phunt@apache.org

Closes #1258 from eolivelli/fix/ZOOKEEPER-3733

Change-Id: I70f4bf96fcd3d8371e1251a60199fe5ef1fdd4d4

pom.xml

@@ -295,6 +295,7 @@
                                     <descriptorRef>${sourceReleaseAssemblyDescriptor}</descriptorRef>
                                 </descriptorRefs>
                                 <finalName>apache-zookeeper-${project.version}</finalName>
+                                <appendAssemblyId>false</appendAssemblyId>
                                 <formats>
                                     <format>tar.gz</format>
                                 </formats>

zookeeper-server/src/main/java/org/apache/zookeeper/version/util/VerGen.java

@@ -80,7 +80,7 @@ public class VerGen {
             w.write("    int MAJOR=" + version.maj + ";\n");
             w.write("    int MINOR=" + version.min + ";\n");
             w.write("    int MICRO=" + version.micro + ";\n");
-            w.write("    String QUALIFIER=" + (version.qualifier == null ? null : "\"" + version.qualifier + "\"") + ";\n");
+            w.write("    String QUALIFIER=" + (version.qualifier == null ? "\"\"" : "\"" + version.qualifier + "\"") + ";\n");
             if (rev.equals("-1")) {
                 System.out.println("Unknown REVISION number, using " + rev);
             }