Wrong operand name displayed when "key=value" syntax is used

[anba]

Multiple OptionHandler sub-classes use Parameters#getParameter(...) with -1 as the index parameter, e.g. EnumOptionHandler. This approach does not work when the "key=value" syntax is used, see splitToken() in CmdLineParser.CmdLineImpl for why this is not working.

[atnak]

FWIW,

Minimal code to reproduce

import org.kohsuke.args4j.CmdLineParser;
import org.kohsuke.args4j.Option;

public class Foo {

    @Option(name = "--foo")
    String foo;

    @Option(name = "--val")
    int val;

    public static void main(String[] args) throws Exception {
        new CmdLineParser(new Foo())
                .parseArgument(new String[] {
                        "--foo=bar",
                        "--val=abc",
                });
    }
}

throws:

org.kohsuke.args4j.CmdLineException: "abc" is not a valid value for "bar"