fixed defaults for Java standard types

https://issues.jenkins-ci.org/browse/JENKINS-31967

plugin/src/main/java/org/jenkinsci/plugins/structs/describable/DescribableModel.java

@@ -9,7 +9,6 @@
import hudson.model.ParameterDefinition;
import hudson.model.ParameterValue;
import hudson.model.ParametersDefinitionProperty;
import hudson.util.ReflectionUtils;
import jenkins.model.Jenkins;
import org.apache.commons.io.IOUtils;
import org.apache.commons.lang.ObjectUtils;
@@ -317,7 +316,7 @@ public T instantiate(Map<String,?> arguments) throws Exception {
            if (a != null) {
                args[i] = coerce(this.type.getName() + "." + name, type, a);
            } else if (type instanceof Class && ((Class) type).isPrimitive()) {
                args[i] = ReflectionUtils.getVmDefaultValueForPrimitiveType((Class)type);
                args[i] = getVmDefaultValueForPrimitiveType((Class)type);
                if (args[i]==null && callEvenIfNoArgs)
                    throw new UnsupportedOperationException("not yet handling @DataBoundConstructor default value of " + type + "; pass an explicit value for " + name);
            } else {
@@ -707,4 +706,22 @@ private Object readResolve() {
    private static final Logger LOGGER = Logger.getLogger(DescribableModel.class.getName());

    private static final long serialVersionUID = 1L;

    /**
     * Given the primitive type, returns the VM default value for that type in a boxed form.
     */
    public static Object getVmDefaultValueForPrimitiveType(Class<?> type) {
        return defaultPrimitiveValue.get(type);
    }

    private static final Map<Class,Object> defaultPrimitiveValue = new HashMap<Class, Object>();
    static {
        defaultPrimitiveValue.put(boolean.class, false);
        defaultPrimitiveValue.put(byte.class, (byte) 0);
        defaultPrimitiveValue.put(short.class, (short) 0);
        defaultPrimitiveValue.put(int.class, 0);
        defaultPrimitiveValue.put(long.class, 0L);
        defaultPrimitiveValue.put(float.class, 0.0f);
        defaultPrimitiveValue.put(double.class, 0.0d);
    }
}