The default value of the RuleParam type parameter is "s" (String)

sonar-plugin-api/src/main/java/org/sonar/api/rules/RuleParam.java

@@ -46,7 +46,7 @@ public class RuleParam {
   private String description;
 
   @Column(name = "param_type", updatable = true, nullable = true, length = 512)
-  private String type;
+  private String type = "s";
 
   @Column(name = "default_value", updatable = true, nullable = true, length = 4000)
   private String defaultValue;