Silence some warnings from IntelliJ

Author: joegallo

modules/ingest-common/src/main/java/org/elasticsearch/ingest/common/ConvertProcessor.java

@@ -118,19 +118,19 @@ public Object convert(Object value) {
                 }
                 try {
                     return BOOLEAN.convert(value);
-                } catch (IllegalArgumentException e) {}
+                } catch (IllegalArgumentException ignored) {}
                 try {
                     return INTEGER.convert(value);
-                } catch (IllegalArgumentException e) {}
+                } catch (IllegalArgumentException ignored) {}
                 try {
                     return LONG.convert(value);
-                } catch (IllegalArgumentException e) {}
+                } catch (IllegalArgumentException ignored) {}
                 try {
                     return FLOAT.convert(value);
-                } catch (IllegalArgumentException e) {}
+                } catch (IllegalArgumentException ignored) {}
                 try {
                     return DOUBLE.convert(value);
-                } catch (IllegalArgumentException e) {}
+                } catch (IllegalArgumentException ignored) {}
                 return value;
             }
         };