diff --git a/data/config-schema/src/main/java/net/corda/schema/configuration/FlowConfig.java b/data/config-schema/src/main/java/net/corda/schema/configuration/FlowConfig.java
index 8a68a0fc4a..67e75825d6 100644
--- a/data/config-schema/src/main/java/net/corda/schema/configuration/FlowConfig.java
+++ b/data/config-schema/src/main/java/net/corda/schema/configuration/FlowConfig.java
@@ -14,5 +14,4 @@ private FlowConfig() {
     public static final String PROCESSING_MAX_RETRY_DELAY = "processing.maxRetryDelay";
     public static final String PROCESSING_MAX_FLOW_SLEEP_DURATION = "processing.maxFlowSleepDuration";
     public static final String PROCESSING_FLOW_CLEANUP_TIME = "processing.cleanupTime";
-    public static final String PROCESSING_THREAD_POOL_SIZE = "processing.poolSize";
 }
diff --git a/data/config-schema/src/main/java/net/corda/schema/configuration/MessagingConfig.java b/data/config-schema/src/main/java/net/corda/schema/configuration/MessagingConfig.java
index ff08267671..a9f95a77dd 100644
--- a/data/config-schema/src/main/java/net/corda/schema/configuration/MessagingConfig.java
+++ b/data/config-schema/src/main/java/net/corda/schema/configuration/MessagingConfig.java
@@ -57,6 +57,8 @@ private Subscription() {
         public static final String SUBSCRIBE_RETRIES = SUBSCRIPTION + ".subscribeRetries";
         public static final String COMMIT_RETRIES = SUBSCRIPTION + ".commitRetries";
         public static final String PROCESSOR_TIMEOUT = SUBSCRIPTION + ".processorTimeout";
+        public static final String PROCESSING_THREAD_POOL_SIZE = SUBSCRIPTION + ".mediator.poolSize";
+        public static final String PROCESSING_MIN_POOL_RECORD_COUNT = SUBSCRIPTION + ".mediator.minPoolRecordCount";
     }
 
     /**
diff --git a/data/config-schema/src/main/resources/net/corda/schema/configuration/messaging/1.0/subscription.json b/data/config-schema/src/main/resources/net/corda/schema/configuration/messaging/1.0/subscription.json
index 14113fdcad..8e66325e83 100644
--- a/data/config-schema/src/main/resources/net/corda/schema/configuration/messaging/1.0/subscription.json
+++ b/data/config-schema/src/main/resources/net/corda/schema/configuration/messaging/1.0/subscription.json
@@ -46,6 +46,27 @@
       "minimum": 1000,
       "maximum": 2147483647,
       "default": 15000
+    },
+    "mediator": {
+      "description": "Settings for the multi source mediator",
+      "type": "object",
+      "default": {},
+      "properties": {
+        "poolSize": {
+          "description": "The size of the mediator event processing pool size.",
+          "type": "integer",
+          "minimum": 1,
+          "maximum": 2147483647,
+          "default": 8
+        },
+        "minPoolRecordCount": {
+          "description": "The minimum number of events in a single mediator processing pool. If the number of records polled is less than this, then the polled records are used in a single pool.",
+          "type": "integer",
+          "minimum": 1,
+          "maximum": 2147483647,
+          "default": 20
+        }
+      }
     }
   },
   "additionalProperties": false
diff --git a/gradle.properties b/gradle.properties
index ff1e9484eb..a3b10d0770 100644
--- a/gradle.properties
+++ b/gradle.properties
@@ -5,7 +5,7 @@ cordaProductVersion = 5.2.0
 # NOTE: update this each time this module contains a breaking change
 ## NOTE: currently this is a top level revision, so all API versions will line up, but this could be moved to
 ##   a per module property in which case module versions can change independently.
-cordaApiRevision = 16
+cordaApiRevision = 17
 
 # Main
 kotlin.stdlib.default.dependency = false