Is there a way to "pivot" a ImmutableMap<String, ImmutableSet<String>>? - guava

Question

I have a ImmutableMap<String, ImmutableSet<String>>. Is there an easy way to "pivot" this kid or do I have to code it myself? I am trying to figure out the best way to view...
{
type1=[FieldA, FieldB, FieldC],
type2=[FieldB, FieldC, FieldD],
type3=[FieldC, FieldD, FieldE]
}
...as...
{
FieldA=[type1],
FieldB=[type1, type2],
FieldC=[type1, type2, type3],
FieldD=[type1, type2],
FieldE=[type3]
}
Does MultiMap solve this problem?

Answer 1

It looks like MultiMap is the way to go. The ImmutableMultiMap#inverse() method is what I was looking for:
ImmutableMultimap.Builder<String, String> builder = new ImmutableMultimap.Builder<String, String>();
builder.putAll( "type1", Arrays.asList( "FieldA", "FieldB", "FieldC") );
builder.putAll( "type2", Arrays.asList( "FieldB", "FieldC", "FieldD") );
builder.putAll( "type3", Arrays.asList( "FieldC", "FieldD", "FieldE") );
ImmutableMultimap<String, String> typesToFields = builder.build();
ImmutableMultimap<String, String> fieldsToTypes = typesToFields.inverse();
System.out.println( "typesToFields: " + typesToFields );
System.out.println( "fieldsToTypes: " + fieldsToTypes );
...produces...
typesToFields: {type1=[FieldA, FieldB, FieldC], type2=[FieldB, FieldC, FieldD], type3=[FieldC, FieldD, FieldE]}
fieldsToTypes: {FieldA=[type1], FieldB=[type1, type2], FieldC=[type1, type2, type3], FieldD=[type2, type3], FieldE=[type3]}