Add IDTokenSource interface

databricks-sdk-java/src/main/java/com/databricks/sdk/core/oauth/IDToken.java

@@ -0,0 +1,22 @@
+package com.databricks.sdk.core.oauth;
+
+/**
+ * Represents an ID Token provided by an identity provider from an OAuth flow.
+ * IDToken is a token that can be exchanged for an access token.
+ */
+public class IDToken {
+    // The string value of the ID Token
+    private final String value;
+
+    /**
+     * Constructs an IDToken with a value.
+     * @param value The ID Token string.
+     */
+    public IDToken(String value) {
+        this.value = value;
+    }
+
+    public String getValue() {
+        return value;
+    }
+}

databricks-sdk-java/src/main/java/com/databricks/sdk/core/oauth/IDTokenSource.java

@@ -0,0 +1,14 @@
+package com.databricks.sdk.core.oauth;
+
+/**
+ * IDTokenSource is anything that returns an IDToken given an audience.
+ */
+public interface IDTokenSource {
+    /**
+     * Retrieves an ID Token for the specified audience.
+     *
+     * @param audience The intended recipient of the ID Token.
+     * @return An {@link IDToken} containing the token value.
+     */
+    IDToken getIDToken(String audience);
+}