Attempt to support invites, working in progress

src/main/groovy/io/kamax/mxisd/exception/ConfigurationException.java

@@ -1,11 +1,27 @@
 package io.kamax.mxisd.exception;
 
+import java.util.Optional;
+
 public class ConfigurationException extends RuntimeException {
 
     private String key;
+    private String detailedMsg;
 
     public ConfigurationException(String key) {
         super("Invalid or empty value for configuration key " + key);
     }
 
+    public ConfigurationException(Throwable t) {
+        super(t.getMessage(), t);
+    }
+
+    public ConfigurationException(String key, String detailedMsg) {
+        this(key);
+        this.detailedMsg = detailedMsg;
+    }
+
+    public Optional<String> getDetailedMessage() {
+        return Optional.ofNullable(detailedMsg);
+    }
+
 }

src/main/groovy/io/kamax/mxisd/exception/MappingAlreadyExistsException.java

@@ -0,0 +1,9 @@
+package io.kamax.mxisd.exception;
+
+public class MappingAlreadyExistsException extends RuntimeException {
+
+    public MappingAlreadyExistsException() {
+        super("A mapping already exists for this 3PID");
+    }
+
+}