Make FieldKey.fromFieldKey return null for invalid input (#2524)

Author: labkey-tchad

src/org/labkey/test/params/FieldKey.java

@@ -2,6 +2,7 @@
 
 import org.apache.commons.lang3.StringUtils;
 import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
 
 import java.util.ArrayList;
 import java.util.Arrays;
@@ -65,15 +66,22 @@ public static FieldKey fromParts(String... parts)
      * @param fieldKey String or FieldKey
      * @return FieldKey representation of the String, or the identity if a FieldKey was provided
      */
-    public static FieldKey fromFieldKey(CharSequence fieldKey)
+    public static @Nullable FieldKey fromFieldKey(CharSequence fieldKey)
     {
         if (fieldKey instanceof WrapsFieldKey fk)
         {
             return fk.getFieldKey();
         }
         else
         {
-            return fromParts(Arrays.stream(fieldKey.toString().split(SEPARATOR)).map(FieldKey::decodePart).toList());
+            try
+            {
+                return fromParts(Arrays.stream(fieldKey.toString().split(SEPARATOR)).map(FieldKey::decodePart).toList());
+            }
+            catch (IllegalArgumentException iae)
+            {
+                return null; // FieldReferenceManager depends on this returning null.
+            }
         }
     }