add multi OAuth2 Provider

src/main/java/stirling/software/SPDF/model/ProviderInterface.java

@@ -0,0 +1,26 @@
+package stirling.software.SPDF.model;
+
+import java.util.Collection;
+
+public interface ProviderInterface {
+
+    public Collection<String> getScopes();
+
+    public void setScopes(String scopes);
+
+    public String getUseAsUsername();
+
+    public void setUseAsUsername(String useAsUsername);
+
+    public String getIssuer();
+
+    public void setIssuer(String issuer);
+
+    public String getClientSecret();
+
+    public void setClientSecret(String clientSecret);
+
+    public String getClientId();
+
+    public void setClientId(String clientId);
+}