Fix quoting in undefined parameters warning log (#2479)

core/src/main/java/hudson/model/ParametersAction.java

@@ -316,7 +316,7 @@ public class ParametersAction implements RunAction2, Iterable<ParameterValue>, Q
             if (this.parameterDefinitionNames.contains(v.getName()) || isSafeParameter(v.getName())) {
                 filteredParameters.add(v);
             } else {
-                LOGGER.log(Level.WARNING, "Skipped parameter `{0}` as it is undefined on `{1}`. Set `-D{2}`=true to allow "
+                LOGGER.log(Level.WARNING, "Skipped parameter `{0}` as it is undefined on `{1}`. Set `-D{2}=true` to allow "
                         + "undefined parameters to be injected as environment variables or `-D{3}=[comma-separated list]` to whitelist specific parameter names, "
                         + "even though it represents a security breach",
                         new Object [] { v.getName(), run.getParent().getFullName(), KEEP_UNDEFINED_PARAMETERS_SYSTEM_PROPERTY_NAME, SAFE_PARAMETERS_SYSTEM_PROPERTY_NAME });