Previous value: -nullNew value: +{
+  "$schema": "http://json-schema.org/draft-07/schema#",
+  "additionalProperties": {},
+  "properties": {
+    "count": {
+      "type": "number"
+    },
+    "coverage": {
+      "additionalProperties": {},
+      "properties": {
+        "status": {
+          "enum": [
+            "complete",
+            "partial"
+          ],
+          "type": "string"
+        },
+        "tracking_since": {
+          "type": "string"
+        },
+        "volcanoes_listed": {
+          "type": "number"
+        },
+        "volcanoes_total": {
+          "type": "number"
+        }
+      },
+      "required": [
+        "status",
+        "tracking_since",
+        "volcanoes_total",
+        "volcanoes_listed"
+      ],
+      "type": "object"
+    },
+    "license_note": {
+      "type": "string"
+    },
+    "note": {
+      "type": "string"
+    },
+    "provenance": {
+      "description": "Freshness receipts for every upstream source used.",
+      "items": {
+        "additionalProperties": {},
+        "description": "Freshness receipt for one upstream source.",
+        "properties": {
+          "content_sha256": {
+            "type": [
+              "string",
+              "null"
+            ]
+          },
+          "fetch_status": {
+            "description": "found / empty / stale / unavailable / unsupported (see catalog fetch_status_values).",
+            "enum": [
+              "found",
+              "empty",
+              "stale",
+              "unavailable",
+              "unsupported"
+            ],
+            "type": "string"
+          },
+          "parser_version": {
+            "type": "string"
+          },
+          "processed_by": {
+            "type": "string"
+          },
+          "retrieved_at": {
+            "description": "When this service retrieved the upstream data (null if unknown).",
+            "type": [
+              "string",
+              "null"
+            ]
+          },
+          "source": {
+            "additionalProperties": {},
+            "description": "Publisher and URL of the upstream document or dataset.",
+            "properties": {
+              "publisher": {
+                "type": "string"
+              },
+              "url": {
+                "type": "string"
+              }
+            },
+            "required": [
+              "publisher",
+              "url"
+            ],
+            "type": "object"
+          },
+          "upstream_updated_at": {
+            "description": "Update time stated by the upstream, or null when it states none.",
+            "type": [
+              "string",
+              "null"
+            ]
+          }
+        },
+        "required": [
+          "source",
+          "upstream_updated_at",
+          "retrieved_at",
+          "content_sha256",
+          "parser_version",
+          "fetch_status",
+          "processed_by"
+        ],
+        "type": "object"
+      },
+      "type": "array"
+    },
+    "responded_at": {
+      "type": "string"
+    },
+    "retrieved_at": {
+      "description": "When the upstream data was retrieved (ISO 8601).",
+      "type": "string"
+    },
+    "source": {
+      "description": "Data source and processor.",
+      "type": "string"
+    },
+    "terms": {
+      "description": "URL of the terms of service.",
+      "type": "string"
+    },
+    "volcanoes": {
+      "description": "One entry per volcano.",
+      "items": {
+        "additionalProperties": {},
+        "properties": {
+          "alert_level": {
+            "description": "Volcanic Alert Level 1-5, or null for volcanoes without levels.",
+            "type": [
+              "number",
+              "null"
+            ]
+          },
+          "code": {
+            "description": "3-digit JMA volcano code.",
+            "type": "string"
+          },
+          "issued_at": {
+            "type": [
+              "string",
+              "null"
+            ]
+          },
+          "name": {
+            "additionalProperties": {},
+            "properties": {
+              "en": {
+                "type": "string"
+              },
+              "ja": {
+                "type": "string"
+              }
+            },
+            "required": [
+              "ja",
+              "en"
+            ],
+            "type": "object"
+          },
+          "provenance": {
+            "description": "Freshness receipts for every upstream source used.",
+            "items": {
+              "additionalProperties": {},
+              "description": "Freshness receipt for one upstream source.",
+              "properties": {
+                "content_sha256": {
+                  "type": [
+                    "string",
+                    "null"
+                  ]
+                },
+                "fetch_status": {
+                  "description": "found / empty / stale / unavailable / unsupported (see catalog fetch_status_values).",
+                  "enum": [
+                    "found",
+                    "empty",
+                    "stale",
+                    "unavailable",
+                    "unsupported"
+                  ],
+                  "type": "string"
+                },
+                "parser_version": {
+                  "type": "string"
+                },
+                "processed_by": {
+                  "type": "string"
+                },
+                "retrieved_at": {
+                  "description": "When this service retrieved the upstream data (null if unknown).",
+                  "type": [
+                    "string",
+                    "null"
+                  ]
+                },
+                "source": {
+                  "additionalProperties": {},
+                  "description": "Publisher and URL of the upstream document or dataset.",
+                  "properties": {
+                    "publisher": {
+                      "type": "string"
+                    },
+                    "url": {
+                      "type": "string"
+                    }
+                  },
+                  "required": [
+                    "publisher",
+                    "url"
+                  ],
+                  "type": "object"
+                },
+                "upstream_updated_at": {
+                  "description": "Update time stated by the upstream, or null when it states none.",
+                  "type": [
+                    "string",
+                    "null"
+                  ]
+                }
+              },
+              "required": [
+                "source",
+                "upstream_updated_at",
+                "retrieved_at",
+                "content_sha256",
+                "parser_version",
+                "fetch_status",
+                "processed_by"
+              ],
+              "type": "object"
+            },
+            "type": "array"
+          },
+          "source_url": {
+            "type": [
+              "string",
+              "null"
+            ]
+          },
+          "status": {
+            "enum": [
+              "listed",
+              "not_seen_in_checked_feeds",
+              "unavailable"
+            ],
+            "type": "string"
+          }
+        },
+        "required": [
+          "code",
+          "name",
+          "status",
+          "alert_level",
+          "issued_at",
+          "source_url",
+          "provenance"
+        ],
+        "type": "object"
+      },
+      "type": "array"
+    }
+  },
+  "required": [
+    "coverage",
+    "count",
+    "volcanoes",
+    "note",
+    "provenance",
+    "source",
+    "retrieved_at",
+    "responded_at",
+    "license_note",
+    "terms"
+  ],
+  "type": "object"
+}