CmdLineParser: Require plugin option names to start with '-'

This is normally a requirement for args4j options, but in the case of
plugin options, the option name is produced by prefixing with
"--myplugin", so an incorrect name in the @Option annotation in a plugin
will not produce an error. Add a manual check for this case, forcing
options to always be named "--myplugin-o" or "--myplugin--opt".

Change-Id: I9e6810ec5470f001b8e772f046e4d3e8be5f7247

java/com/google/gerrit/util/cli/CmdLineParser.java

@@ -34,6 +34,7 @@
 
 package com.google.gerrit.util.cli;
 
+import static com.google.common.base.Preconditions.checkArgument;
 import static com.google.gerrit.util.cli.Localizable.localizable;
 
 import com.google.common.base.Strings;
@@ -426,6 +427,7 @@ public class CmdLineParser {
 
     PrefixedOption(String prefix, Option o) {
       this.prefix = prefix;
+      checkArgument(o.name().startsWith("-"), "Option name must start with '-': %s", o);
       this.o = o;
     }