@Override
    public ValueExpression setVariable(String variable, ValueExpression expression) {
        return map.put(variable, expression);
    }
Sets a variable which can be resolved

@param variable   variable name
@param expression expression to assign
@return the previous resolved {@link ValueExpression} assigned to the variable, null if none
core/src/main/java/com/github/dozermapper/core/el/mappers/VariablesMapper.java