private static <T> T throwingMerger(T one, T two) {
        throw new IllegalStateException("Duplicate key " + one);
    }
Helper function, that represents a BinaryOperator for use in Collectors.toMap() that assumes that there are no duplicate keys.

@param <T> key value type
@param one first key occurrence
@param two second key occurrence
@return nothing, as this always throws an IllegalStateException when invoked
jsonschema-generator/src/main/java/com/github/victools/jsonschema/generator/impl/SchemaCleanUpUtils.java