diff --git a/rest-api-spec/src/main/resources/rest-api-spec/api/cat.aliases.json b/rest-api-spec/src/main/resources/rest-api-spec/api/cat.aliases.json
index ee1e083a1e2a2..daa9596541e10 100644
--- a/rest-api-spec/src/main/resources/rest-api-spec/api/cat.aliases.json
+++ b/rest-api-spec/src/main/resources/rest-api-spec/api/cat.aliases.json
@@ -37,6 +37,7 @@
     "params": {
       "format": {
         "type": "string",
+        "default": "text",
         "description": "a short version of the Accept header, e.g. json, yaml"
       },
       "h": {
diff --git a/rest-api-spec/src/main/resources/rest-api-spec/api/cat.allocation.json b/rest-api-spec/src/main/resources/rest-api-spec/api/cat.allocation.json
index d373fa8b36114..cea2287422074 100644
--- a/rest-api-spec/src/main/resources/rest-api-spec/api/cat.allocation.json
+++ b/rest-api-spec/src/main/resources/rest-api-spec/api/cat.allocation.json
@@ -37,6 +37,7 @@
     "params": {
       "format": {
         "type": "string",
+        "default": "text",
         "description": "a short version of the Accept header, e.g. json, yaml"
       },
       "bytes": {
diff --git a/rest-api-spec/src/main/resources/rest-api-spec/api/cat.component_templates.json b/rest-api-spec/src/main/resources/rest-api-spec/api/cat.component_templates.json
index 3ecf330366d4c..b4434ccca69b7 100644
--- a/rest-api-spec/src/main/resources/rest-api-spec/api/cat.component_templates.json
+++ b/rest-api-spec/src/main/resources/rest-api-spec/api/cat.component_templates.json
@@ -37,6 +37,7 @@
     "params": {
       "format": {
         "type": "string",
+        "default": "text",
         "description": "a short version of the Accept header, e.g. json, yaml"
       },
       "local": {
diff --git a/rest-api-spec/src/main/resources/rest-api-spec/api/cat.count.json b/rest-api-spec/src/main/resources/rest-api-spec/api/cat.count.json
index f658af56438f8..d4714e43b3709 100644
--- a/rest-api-spec/src/main/resources/rest-api-spec/api/cat.count.json
+++ b/rest-api-spec/src/main/resources/rest-api-spec/api/cat.count.json
@@ -37,6 +37,7 @@
     "params": {
       "format": {
         "type": "string",
+        "default": "text",
         "description": "a short version of the Accept header, e.g. json, yaml"
       },
       "h": {
diff --git a/rest-api-spec/src/main/resources/rest-api-spec/api/cat.fielddata.json b/rest-api-spec/src/main/resources/rest-api-spec/api/cat.fielddata.json
index 4a43bbdf30a40..a07abb4322542 100644
--- a/rest-api-spec/src/main/resources/rest-api-spec/api/cat.fielddata.json
+++ b/rest-api-spec/src/main/resources/rest-api-spec/api/cat.fielddata.json
@@ -37,6 +37,7 @@
     "params": {
       "format": {
         "type": "string",
+        "default": "text",
         "description": "a short version of the Accept header, e.g. json, yaml"
       },
       "bytes": {
diff --git a/rest-api-spec/src/main/resources/rest-api-spec/api/cat.health.json b/rest-api-spec/src/main/resources/rest-api-spec/api/cat.health.json
index 8a1e798496000..383a87b0ddb7b 100644
--- a/rest-api-spec/src/main/resources/rest-api-spec/api/cat.health.json
+++ b/rest-api-spec/src/main/resources/rest-api-spec/api/cat.health.json
@@ -25,6 +25,7 @@
     "params": {
       "format": {
         "type": "string",
+        "default": "text",
         "description": "a short version of the Accept header, e.g. json, yaml"
       },
       "h": {
diff --git a/rest-api-spec/src/main/resources/rest-api-spec/api/cat.indices.json b/rest-api-spec/src/main/resources/rest-api-spec/api/cat.indices.json
index 157b742096f04..4ab12ea4f6e7c 100644
--- a/rest-api-spec/src/main/resources/rest-api-spec/api/cat.indices.json
+++ b/rest-api-spec/src/main/resources/rest-api-spec/api/cat.indices.json
@@ -37,6 +37,7 @@
     "params": {
       "format": {
         "type": "string",
+        "default": "text",
         "description": "a short version of the Accept header, e.g. json, yaml"
       },
       "bytes": {
diff --git a/rest-api-spec/src/main/resources/rest-api-spec/api/cat.master.json b/rest-api-spec/src/main/resources/rest-api-spec/api/cat.master.json
index 9240a97282346..e5753f3913e09 100644
--- a/rest-api-spec/src/main/resources/rest-api-spec/api/cat.master.json
+++ b/rest-api-spec/src/main/resources/rest-api-spec/api/cat.master.json
@@ -25,6 +25,7 @@
     "params": {
       "format": {
         "type": "string",
+        "default": "text",
         "description": "a short version of the Accept header, e.g. json, yaml"
       },
       "local": {
diff --git a/rest-api-spec/src/main/resources/rest-api-spec/api/cat.ml_data_frame_analytics.json b/rest-api-spec/src/main/resources/rest-api-spec/api/cat.ml_data_frame_analytics.json
index 42971490b98fa..b11ffe18eee76 100644
--- a/rest-api-spec/src/main/resources/rest-api-spec/api/cat.ml_data_frame_analytics.json
+++ b/rest-api-spec/src/main/resources/rest-api-spec/api/cat.ml_data_frame_analytics.json
@@ -59,6 +59,7 @@
       },
       "format": {
         "type": "string",
+        "default": "text",
         "description": "a short version of the Accept header, e.g. json, yaml"
       },
       "h": {
diff --git a/rest-api-spec/src/main/resources/rest-api-spec/api/cat.ml_datafeeds.json b/rest-api-spec/src/main/resources/rest-api-spec/api/cat.ml_datafeeds.json
index 2d4807d4d8f0f..7b81872cbaebc 100644
--- a/rest-api-spec/src/main/resources/rest-api-spec/api/cat.ml_datafeeds.json
+++ b/rest-api-spec/src/main/resources/rest-api-spec/api/cat.ml_datafeeds.json
@@ -42,6 +42,7 @@
       },
       "format": {
         "type": "string",
+        "default": "text",
         "description": "a short version of the Accept header, e.g. json, yaml"
       },
       "h": {
diff --git a/rest-api-spec/src/main/resources/rest-api-spec/api/cat.ml_jobs.json b/rest-api-spec/src/main/resources/rest-api-spec/api/cat.ml_jobs.json
index ffeb53c375e0f..5a238732ac3c7 100644
--- a/rest-api-spec/src/main/resources/rest-api-spec/api/cat.ml_jobs.json
+++ b/rest-api-spec/src/main/resources/rest-api-spec/api/cat.ml_jobs.json
@@ -59,6 +59,7 @@
       },
       "format": {
         "type": "string",
+        "default": "text",
         "description": "a short version of the Accept header, e.g. json, yaml"
       },
       "h": {
diff --git a/rest-api-spec/src/main/resources/rest-api-spec/api/cat.ml_trained_models.json b/rest-api-spec/src/main/resources/rest-api-spec/api/cat.ml_trained_models.json
index 7e04a7138adbc..9fdd38f75ea33 100644
--- a/rest-api-spec/src/main/resources/rest-api-spec/api/cat.ml_trained_models.json
+++ b/rest-api-spec/src/main/resources/rest-api-spec/api/cat.ml_trained_models.json
@@ -70,6 +70,7 @@
       },
       "format": {
         "type": "string",
+        "default": "text",
         "description": "a short version of the Accept header, e.g. json, yaml"
       },
       "h": {
diff --git a/rest-api-spec/src/main/resources/rest-api-spec/api/cat.nodeattrs.json b/rest-api-spec/src/main/resources/rest-api-spec/api/cat.nodeattrs.json
index 634dc194ff283..382da2d5fd962 100644
--- a/rest-api-spec/src/main/resources/rest-api-spec/api/cat.nodeattrs.json
+++ b/rest-api-spec/src/main/resources/rest-api-spec/api/cat.nodeattrs.json
@@ -25,6 +25,7 @@
     "params": {
       "format": {
         "type": "string",
+        "default": "text",
         "description": "a short version of the Accept header, e.g. json, yaml"
       },
       "local": {
diff --git a/rest-api-spec/src/main/resources/rest-api-spec/api/cat.nodes.json b/rest-api-spec/src/main/resources/rest-api-spec/api/cat.nodes.json
index 14ee0cc632350..4e1c9884682ed 100644
--- a/rest-api-spec/src/main/resources/rest-api-spec/api/cat.nodes.json
+++ b/rest-api-spec/src/main/resources/rest-api-spec/api/cat.nodes.json
@@ -42,6 +42,7 @@
       },
       "format": {
         "type": "string",
+        "default": "text",
         "description": "a short version of the Accept header, e.g. json, yaml"
       },
       "full_id": {
diff --git a/rest-api-spec/src/main/resources/rest-api-spec/api/cat.pending_tasks.json b/rest-api-spec/src/main/resources/rest-api-spec/api/cat.pending_tasks.json
index 92412071580cc..eda787899f93d 100644
--- a/rest-api-spec/src/main/resources/rest-api-spec/api/cat.pending_tasks.json
+++ b/rest-api-spec/src/main/resources/rest-api-spec/api/cat.pending_tasks.json
@@ -25,6 +25,7 @@
     "params": {
       "format": {
         "type": "string",
+        "default": "text",
         "description": "a short version of the Accept header, e.g. json, yaml"
       },
       "local": {
diff --git a/rest-api-spec/src/main/resources/rest-api-spec/api/cat.plugins.json b/rest-api-spec/src/main/resources/rest-api-spec/api/cat.plugins.json
index 2c6975a7f65b2..5b56e63901634 100644
--- a/rest-api-spec/src/main/resources/rest-api-spec/api/cat.plugins.json
+++ b/rest-api-spec/src/main/resources/rest-api-spec/api/cat.plugins.json
@@ -25,6 +25,7 @@
     "params": {
       "format": {
         "type": "string",
+        "default": "text",
         "description": "a short version of the Accept header, e.g. json, yaml"
       },
       "local": {
diff --git a/rest-api-spec/src/main/resources/rest-api-spec/api/cat.recovery.json b/rest-api-spec/src/main/resources/rest-api-spec/api/cat.recovery.json
index b01defb8400d2..4c33d0d5dffa7 100644
--- a/rest-api-spec/src/main/resources/rest-api-spec/api/cat.recovery.json
+++ b/rest-api-spec/src/main/resources/rest-api-spec/api/cat.recovery.json
@@ -37,6 +37,7 @@
     "params": {
       "format": {
         "type": "string",
+        "default": "text",
         "description": "a short version of the Accept header, e.g. json, yaml"
       },
       "active_only": {
diff --git a/rest-api-spec/src/main/resources/rest-api-spec/api/cat.repositories.json b/rest-api-spec/src/main/resources/rest-api-spec/api/cat.repositories.json
index cf3ae7463ad7d..a432a3379516f 100644
--- a/rest-api-spec/src/main/resources/rest-api-spec/api/cat.repositories.json
+++ b/rest-api-spec/src/main/resources/rest-api-spec/api/cat.repositories.json
@@ -25,6 +25,7 @@
     "params": {
       "format": {
         "type": "string",
+        "default": "text",
         "description": "a short version of the Accept header, e.g. json, yaml"
       },
       "local": {
diff --git a/rest-api-spec/src/main/resources/rest-api-spec/api/cat.segments.json b/rest-api-spec/src/main/resources/rest-api-spec/api/cat.segments.json
index 997408b7e6d53..89b5795844108 100644
--- a/rest-api-spec/src/main/resources/rest-api-spec/api/cat.segments.json
+++ b/rest-api-spec/src/main/resources/rest-api-spec/api/cat.segments.json
@@ -37,6 +37,7 @@
     "params": {
       "format": {
         "type": "string",
+        "default": "text",
         "description": "a short version of the Accept header, e.g. json, yaml"
       },
       "local": {
diff --git a/rest-api-spec/src/main/resources/rest-api-spec/api/cat.shards.json b/rest-api-spec/src/main/resources/rest-api-spec/api/cat.shards.json
index 78ed6be27df0d..6e02c868df978 100644
--- a/rest-api-spec/src/main/resources/rest-api-spec/api/cat.shards.json
+++ b/rest-api-spec/src/main/resources/rest-api-spec/api/cat.shards.json
@@ -37,6 +37,7 @@
     "params": {
       "format": {
         "type": "string",
+        "default": "text",
         "description": "a short version of the Accept header, e.g. json, yaml"
       },
       "bytes": {
diff --git a/rest-api-spec/src/main/resources/rest-api-spec/api/cat.snapshots.json b/rest-api-spec/src/main/resources/rest-api-spec/api/cat.snapshots.json
index c0aaa4143fce6..024aaee557929 100644
--- a/rest-api-spec/src/main/resources/rest-api-spec/api/cat.snapshots.json
+++ b/rest-api-spec/src/main/resources/rest-api-spec/api/cat.snapshots.json
@@ -37,6 +37,7 @@
     "params": {
       "format": {
         "type": "string",
+        "default": "text",
         "description": "a short version of the Accept header, e.g. json, yaml"
       },
       "ignore_unavailable": {
diff --git a/rest-api-spec/src/main/resources/rest-api-spec/api/cat.tasks.json b/rest-api-spec/src/main/resources/rest-api-spec/api/cat.tasks.json
index e7e4c40376391..3aef3ea4f4801 100644
--- a/rest-api-spec/src/main/resources/rest-api-spec/api/cat.tasks.json
+++ b/rest-api-spec/src/main/resources/rest-api-spec/api/cat.tasks.json
@@ -25,6 +25,7 @@
     "params": {
       "format": {
         "type": "string",
+        "default": "text",
         "description": "a short version of the Accept header, e.g. json, yaml"
       },
       "nodes": {
diff --git a/rest-api-spec/src/main/resources/rest-api-spec/api/cat.templates.json b/rest-api-spec/src/main/resources/rest-api-spec/api/cat.templates.json
index 7bf67a68646ac..ab5136d46230c 100644
--- a/rest-api-spec/src/main/resources/rest-api-spec/api/cat.templates.json
+++ b/rest-api-spec/src/main/resources/rest-api-spec/api/cat.templates.json
@@ -37,6 +37,7 @@
     "params": {
       "format": {
         "type": "string",
+        "default": "text",
         "description": "a short version of the Accept header, e.g. json, yaml"
       },
       "local": {
diff --git a/rest-api-spec/src/main/resources/rest-api-spec/api/cat.thread_pool.json b/rest-api-spec/src/main/resources/rest-api-spec/api/cat.thread_pool.json
index 8014d559b91d1..e2e21165c7e7a 100644
--- a/rest-api-spec/src/main/resources/rest-api-spec/api/cat.thread_pool.json
+++ b/rest-api-spec/src/main/resources/rest-api-spec/api/cat.thread_pool.json
@@ -37,6 +37,7 @@
     "params": {
       "format": {
         "type": "string",
+        "default": "text",
         "description": "a short version of the Accept header, e.g. json, yaml"
       },
       "time": {
diff --git a/rest-api-spec/src/main/resources/rest-api-spec/api/cat.transforms.json b/rest-api-spec/src/main/resources/rest-api-spec/api/cat.transforms.json
index db80777264f10..624544deec842 100644
--- a/rest-api-spec/src/main/resources/rest-api-spec/api/cat.transforms.json
+++ b/rest-api-spec/src/main/resources/rest-api-spec/api/cat.transforms.json
@@ -52,6 +52,7 @@
       },
       "format": {
         "type": "string",
+        "default": "text",
         "description": "a short version of the Accept header, e.g. json, yaml"
       },
       "h": {