oauth2/oauth2-client/src/main/java/org/springframework/security/oauth2/client/web/HttpSessionOAuth2AuthorizationRequestRepository.java
private Map<String, OAuth2AuthorizationRequest> getAuthorizationRequests(HttpServletRequest request) {
		HttpSession session = request.getSession(false);
		Map<String, OAuth2AuthorizationRequest> authorizationRequests = session == null ? null :
				(Map<String, OAuth2AuthorizationRequest>) session.getAttribute(this.sessionAttributeName);
		if (authorizationRequests == null) {
			return new HashMap<>();
		}
		return authorizationRequests;
	}
private Map<String, OAuth2AuthorizationRequest> getAuthorizationRequests(HttpServletRequest request) {
		HttpSession session = request.getSession(false);
		Map<String, OAuth2AuthorizationRequest> authorizationRequests = session == null ? null :
				(Map<String, OAuth2AuthorizationRequest>) session.getAttribute(this.sessionAttributeName);
		if (authorizationRequests == null) {
			return new HashMap<>();
		}
		return authorizationRequests;
	}
Gets a non-null and mutable map of {@link OAuth2AuthorizationRequest#getState()} to an {@link OAuth2AuthorizationRequest}
@param request
@return a non-null and mutable map of {@link OAuth2AuthorizationRequest#getState()} to an {@link OAuth2AuthorizationRequest}.