expose failure reason when flag parsing fails (#380)

CHANGELOG.md

@@ -6,6 +6,9 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Added
+- Core: Expose failure reason when flag parsing fails ([#380](https://github.com/Incendo/cloud/pull/380))
+
 ## [1.7.1]
 
 ### Added

cloud-core/src/main/java/cloud/commandframework/arguments/compound/FlagArgument.java

@@ -483,6 +483,7 @@ public final class FlagArgument<C> extends CommandArgument<C, Object> {
 
         private static final long serialVersionUID = -7725389394142868549L;
         private final String input;
+        private final FailureReason failureReason;
 
         /**
          * Construct a new flag parse exception
@@ -504,6 +505,7 @@ public final class FlagArgument<C> extends CommandArgument<C, Object> {
                     CaptionVariable.of("flag", input)
             );
             this.input = input;
+            this.failureReason = failureReason;
         }
 
         /**
@@ -514,6 +516,17 @@ public final class FlagArgument<C> extends CommandArgument<C, Object> {
         public String getInput() {
             return this.input;
         }
+
+        /**
+         * Returns the reason why the flag parsing failed.
+         *
+         * @return the failure reason
+         * @since 1.8.0
+         */
+        @API(status = API.Status.STABLE, since = "1.8.0")
+        public @NonNull FailureReason failureReason() {
+            return this.failureReason;
+        }
     }