Parser
it would be nice to have a parser for (fragments of) mustache JSON/YAML files. This would make it much easier to create constant segments.
Example:
MappingElement ipElement = new MappingElement();
ipElement.addKeyValuePair("name", ValueElement.of("AXIS_to_image");
ipElement.addKeyValuePair("ID", ValueElement.of(3));
ipElement.addKeyValuePair("type", ValueElement.of("subscriber"));
could become
MappingElement ipElement = MappingElement.parse("{name: AXIS_to_image, ID: 3, type: subscriber}");
JSON would be enough (and even better than indentation-formatted YAML because of the lack of multi-line Strings in Java).
There could be
static MappingElement MappingElement.parse(String s);
static KeyValuePair KeyValuePair.parse(String s);
static ListElement ListElement.parse(String s);
For the sake of completeness maybe also
static Document Document.parse(Sring filename, String s);