We are trying to iterate over a `Map`, but without any success. We reduced our issue to this minimal example:

```
def map = [
           'monday': 'mon',
           'tuesday': 'tue',
           ]

```

If we try to iterate with:

```
map.each{ k, v -> println "${k}:${v}" }

```

Only the first entry is output: `monday:mon`

---

The alternatives we know of are not even able to enter the loop:

```
for (e in map)
{
    println "key = ${e.key}, value = ${e.value}"
}

```

or

```
for (Map.Entry<String, String> e: map.entrySet())
{
    println "key = ${e.key}, value = ${e.value}"
}

```

Are failing, both only showing the exception `java.io.NotSerializableException: java.util.LinkedHashMap$Entry`. (which could be related to an exception occurring while raising the 'real' exception, preventing us from knowing what happened).

We are using latest stable jenkins (2.19.1) with all plugins up-to-date as of today (2016/10/20).

Is there a solution to iterate over elements in a `Map` within a Jenkins pipeline Groovy script ?