Use padding for J.Assert#detail model

rewrite-java/src/main/java/org/openrewrite/java/JavaPrinter.java

@@ -227,7 +227,7 @@ public J visitAssert(Assert assert_, PrintOutputCapture<P> p) {
         beforeSyntax(assert_, Space.Location.ASSERT_PREFIX, p);
         p.append("assert");
         visit(assert_.getCondition(), p);
-        visitLeftPadded(":", assert_.getDetail(), JLeftPadded.Location.ASSERT_DETAIL, p);
+        visitLeftPadded(":", assert_.getPadding().getDetail(), JLeftPadded.Location.ASSERT_DETAIL, p);
         afterSyntax(assert_, p);
         return assert_;
     }

rewrite-java/src/main/java/org/openrewrite/java/JavaVisitor.java

@@ -315,7 +315,7 @@ public J visitAssert(J.Assert assert_, P p) {
         }
         a = a.withCondition(visitAndCast(a.getCondition(), p));
         if (a.getDetail() != null) {
-            a = a.withDetail(visitLeftPadded(a.getDetail(), JLeftPadded.Location.ASSERT_DETAIL, p));
+            a = a.getPadding().withDetail(visitLeftPadded(a.getPadding().getDetail(), JLeftPadded.Location.ASSERT_DETAIL, p));
         }
         return a;
     }

rewrite-java/src/main/java/org/openrewrite/java/search/SemanticallyEqual.java

@@ -249,7 +249,7 @@ public J.Assert visitAssert(J.Assert _assert, J j) {
 
                 visit(_assert.getCondition(), compareTo.getCondition());
                 if (_assert.getDetail() != null && compareTo.getDetail() != null) {
-                    visit(_assert.getDetail().getElement(), compareTo.getDetail().getElement());
+                    visit(_assert.getDetail(), compareTo.getDetail());
                 }
             }
             return _assert;

rewrite-java/src/main/java/org/openrewrite/java/tree/J.java

@@ -411,25 +411,41 @@ public CoordinateBuilder.Expression getCoordinates() {
 
     @FieldDefaults(makeFinal = true, level = AccessLevel.PRIVATE)
     @EqualsAndHashCode(callSuper = false, onlyExplicitlyIncluded = true)
-    @Data
+    @RequiredArgsConstructor
+    @AllArgsConstructor(access = AccessLevel.PRIVATE)
     final class Assert implements J, Statement {
+        @Nullable
+        @NonFinal
+        transient WeakReference<Padding> padding;
+
         @With
+        @Getter
         @EqualsAndHashCode.Include
         UUID id;
 
         @With
+        @Getter
         Space prefix;
 
         @With
+        @Getter
         Markers markers;
 
         @With
+        @Getter
         Expression condition;
 
         @Nullable
-        @With
         JLeftPadded<Expression> detail;
 
+        public @Nullable Expression getDetail() {
+            return detail != null ? detail.getElement() : null;
+        }
+
+        public Assert withDetail(@Nullable Expression detail) {
+            return getPadding().withDetail(JLeftPadded.withElement(this.detail, detail));
+        }
+
         @Override
         public <P> J acceptJava(JavaVisitor<P> v, P p) {
             return v.visitAssert(this, p);
@@ -441,10 +457,38 @@ public CoordinateBuilder.Statement getCoordinates() {
             return new CoordinateBuilder.Statement(this);
         }
 
+        public Padding getPadding() {
+            Padding p;
+            if (this.padding == null) {
+                p = new Padding(this);
+                this.padding = new WeakReference<>(p);
+            } else {
+                p = this.padding.get();
+                if (p == null || p.t != this) {
+                    p = new Padding(this);
+                    this.padding = new WeakReference<>(p);
+                }
+            }
+            return p;
+        }
+
         @Override
         public String toString() {
             return withPrefix(Space.EMPTY).printTrimmed(new JavaPrinter<>());
         }
+
+        @RequiredArgsConstructor
+        public static class Padding {
+            private final Assert t;
+
+            public @Nullable JLeftPadded<Expression> getDetail() {
+                return t.detail;
+            }
+
+            public Assert withDetail(@Nullable JLeftPadded<Expression> detail) {
+                return t.detail == detail ? t : new Assert(t.id, t.prefix, t.markers, t.condition, detail);
+            }
+        }
     }
 
     @FieldDefaults(makeFinal = true, level = AccessLevel.PRIVATE)