A representation of source input to GraphQL.
name and locationOffset are optional. They are useful for clients who
store GraphQL documents in source files; for example, if the GraphQL input
starts at line 40 in a file named Foo.graphql, it might be useful for name to
be "Foo.graphql" and location to be { line: 40, column: 1 }.
line and column in locationOffset are 1-indexed