@@ -1,7 +1,6 @@
 from __future__ import annotations
 
 import builtins
-import dataclasses
 import email.feedparser
 import email.header
 import email.message
@@ -274,34 +273,6 @@ def _get_payload(msg: email.message.Message, source: bytes | str) -> str:
 _MULTI_FIELDS = {_RAW_TO_EMAIL_MAPPING[x] for x in _LIST_FIELDS | _DICT_FIELDS}
 
 
-@dataclasses.dataclass
-class _JSonMessageSetter:
-    """
-    This provides an API to build a JSON message output in the same way as the
-    classic Message. Line breaks are preserved this way.
-    """
-
-    data: dict[str, str | list[str]]
-
-    def __setitem__(self, name: str, value: str | None) -> None:
-        key = name.replace("-", "_")
-        if value is None:
-            return
-
-        if name == "keywords":
-            values = (x.strip() for x in value.split(","))
-            self.data[key] = [x for x in values if x]
-        elif name in _MULTI_FIELDS:
-            entry = self.data.setdefault(key, [])
-            assert isinstance(entry, list)
-            entry.append(value)
-        else:
-            self.data[key] = value
-
-    def set_payload(self, payload: str) -> None:
-        self["description"] = payload
-
-
 # This class is for writing RFC822 messages
 class RFC822Policy(email.policy.EmailPolicy):
     """
@@ -883,16 +854,7 @@ def as_rfc822(self) -> RFC822Message:
         self._write_metadata(message)
         return message
 
-    def as_json(self) -> dict[str, str | list[str]]:
-        """
-        Return a JSON message with the metadata.
-        """
-        message: dict[str, str | list[str]] = {}
-        smart_message = _JSonMessageSetter(message)
-        self._write_metadata(smart_message)
-        return message
-
-    def _write_metadata(self, message: RFC822Message | _JSonMessageSetter) -> None:
+    def _write_metadata(self, message: RFC822Message) -> None:
         """
         Return an RFC822 message with the metadata.
         """
 
@@ -715,42 +715,6 @@ def test_large(self):
             }
         )
 
-        assert meta.as_json() == {
-            "author": "Example!",
-            "author_email": "Unknown <example@example.com>",
-            "classifier": [
-                "Development Status :: 4 - Beta",
-                "Programming Language :: Python",
-            ],
-            "description": "some readme 👋\n",
-            "description_content_type": "text/markdown",
-            "keywords": ["trampolim", "is", "interesting"],
-            "license": "some license text",
-            "maintainer_email": "Other Example <other@example.com>",
-            "metadata_version": "2.1",
-            "name": "full_metadata",
-            "project_url": [
-                "homepage, example.com",
-                "documentation, readthedocs.org",
-                "repository, github.com/some/repo",
-                "changelog, github.com/some/repo/blob/master/CHANGELOG.rst",
-            ],
-            "provides_extra": ["test"],
-            "requires_dist": [
-                "dependency1",
-                "dependency2>1.0.0",
-                "dependency3[extra]",
-                'dependency4; os_name != "nt"',
-                'dependency5[other-extra]>1.0; os_name == "nt"',
-                'test_dependency; extra == "test"',
-                'test_dependency[test_extra]; extra == "test"',
-                'test_dependency[test_extra2]>3.0; os_name == "nt" and extra == "test"',
-            ],
-            "requires_python": ">=3.8",
-            "summary": "A package with all the metadata :)",
-            "version": "3.2.1",
-        }
-
         core_metadata = meta.as_rfc822()
         assert core_metadata.items() == [
             ("metadata-version", "2.1"),