Literals
A literal is an expression that is expected in a schema as it appears in the concepts definition. Below definition has sayHello, name and string as literals.
CONCEPTS: service.concepts.json
{
"sayHello": {
"name": "string"
}
}
Literals on the left-hand side are called key literals, literals on the right-hand side are called value literals. So sayHello and name are key literals, string is a value literal.
Since this concepts definition consists of only literals, it only validates itself;
SCHEMA: greeting.service.json
{
"sayHello": {
"name": "string"
}
}