java-authenticationlisted

# Authenticating an APIMatic Java SDK client > **This API declares at least one security scheme**, so everything below applies to this SDK: > `<root>/authentication/` exists and `{Api}Client.Builder` carries a credential setter per scheme. Read > those setters for the real names. How you authenticate depends on the security scheme(s) the API uses. APIMatic surfaces each scheme as a **`{Scheme}Model` data class plus a matching setter on the client `Builder`**. Set the ones your API uses when you build the client (see `java-client-initialization`). To see which schemes a specific SDK accepts, read the **credential setters on `{Api}Client.Builder`** — those are the source of truth. The models live in `<root>/authentication/`; the credentials *interface* sits in the root package when the API has a single scheme and in `<root>/authentication/` when it has several. `doc/auth/*.md` lists the same set in readable form. ## The universal shape Every scheme follows the same three steps: build the model, pass it to the client builder, forget about it. ```java import {rootPackage}.{Api}Client; import {rootPackage}.authentication.{Scheme}Model; {Api}Client client = new {Api}Client.Builder() .{scheme}Credentials(new {Scheme}Model.Builder( System.getenv("API_CLIENT_ID"), // required credentials: Builder constructor System.getenv("API_CLIENT_SECRET")) .build()) .build(); ``` - **Required credentials ar