parsePresetValue constructs a GraphQL value when an input value definition contains a preset with it. This function checks if the given preset value is a legal value to the field that's specified it. For example: A scalar input value cannot contain an input object value. When the preset value is a session variable, we treat it as a session variable whose value will be resolved while the query is executed. In the case of session variables preset, we make the GraphQL value as a Variable value and during the execution we resolve all these "session variable" variable(s) and then query the remote server.

validateDirective checks if the arguments of a given directive is a subset of the corresponding upstream directive arguments *NOTE*: This function assumes that the providedDirective and the upstreamDirective have the same name.

validateDirectives checks if the providedDirectives are a subset of upstreamDirectives and then validate each of the directives by calling the validateDirective

validateEnumTypeDefinition checks the validity of an enum definition provided by the user against the corresponding upstream enum. The function does the following things: 1. Validates the directives (if any) 2. For each enum provided, check if the enum values are a subset of the enum values of the corresponding upstream enum *NOTE*: This function assumes that the providedEnum and the upstreamEnum have the same name.

validateInputValueDefinition validates a given input value definition , against the corresponding upstream input value definition. Two things are validated to do the same, the type and the default value of the input value definitions should be equal.

validateArguments validates the provided arguments against the corresponding upstream remote schema arguments.

helper function to validate the schema definitions mentioned in the schema document.

Construction of the possibleTypes map for interfaces, while parsing the user provided Schema document, it doesn't include the possibleTypes, so constructing here, manually.

getSchemaDocIntrospection converts the PartitionedTypeDefinitions to IntrospectionResult because the function buildRemoteParser function which builds the remote schema parsers accepts an IntrospectionResult. The conversion involves converting `G.TypeDefinition ()` to `G.TypeDefinition [G.Name]`. The `[G.Name]` here being the list of object names that an interface implements. This is needed to be done here by-hand because while specifying the SchemaDocument through the GraphQL DSL, it doesn't include the possibleTypes along with an object.

validateRemoteSchema accepts two arguments, the SchemaDocument of the role-based schema, that is provided by the user and the SchemaIntrospection of the upstream remote schema. This function, in turn calls the other validation functions for scalars, enums, unions, interfaces,input objects and objects.