InputLocation location = plugins.get(key).getLocation("");
                problems.add(
                        Severity.WARNING,
                        ModelProblem.Version.V20,
                        "'build.plugins.plugin.version' for " + key + " is missing.",
                        location);
            }
        }
    }

                        // use key as is
                    }
                }

                location = tracker.getLocation(key);
            }

            if (location == null) {
                location = tracker.getLocation(EMPTY);
            }
        }

        return location;
    }

    private static boolean equals(String s1, String s2) {