GH-3129: Use VARCHAR2 for non-fixed strings (#3133)

Fixes #3129

The `CHAR` type in Oracle is for fixed length values.
If the value is not of expected length it is padded with whitespaces.
This causes wrong assumptions when we perform queries against tables.

* Change the `CHAR` into a `VARCHAR2` in those tables for Oracle
where we don't have values with a fixed length.
In fact only `MESSAGE_ID` comes with always fixed length as `36`
because it is fully based on the `UUID`

Author: artembilan

spring-integration-jdbc/src/main/resources/org/springframework/integration/jdbc/schema-oracle.sql

@@ -9,14 +9,14 @@ CREATE TABLE INT_MESSAGE  (
 CREATE INDEX INT_MESSAGE_IX1 ON INT_MESSAGE (CREATED_DATE);
 
 CREATE TABLE INT_GROUP_TO_MESSAGE  (
-	GROUP_KEY CHAR(36) NOT NULL,
+	GROUP_KEY VARCHAR2(36) NOT NULL,
 	MESSAGE_ID CHAR(36) NOT NULL,
 	REGION VARCHAR2(100),
 	constraint INT_GROUP_TO_MESSAGE_PK primary key (GROUP_KEY, MESSAGE_ID, REGION)
 );
 
 CREATE TABLE INT_MESSAGE_GROUP  (
-	GROUP_KEY CHAR(36) NOT NULL,
+	GROUP_KEY VARCHAR2(36) NOT NULL,
 	REGION VARCHAR2(100) NOT NULL,
 	MARKED NUMBER(19,0),
 	COMPLETE NUMBER(19,0),
@@ -27,9 +27,9 @@ CREATE TABLE INT_MESSAGE_GROUP  (
 );
 
 CREATE TABLE INT_LOCK  (
-	LOCK_KEY CHAR(36) NOT NULL,
+	LOCK_KEY VARCHAR2(36) NOT NULL,
 	REGION VARCHAR2(100) NOT NULL,
-	CLIENT_ID CHAR(36),
+	CLIENT_ID VARCHAR2(36),
 	CREATED_DATE TIMESTAMP NOT NULL,
 	constraint INT_LOCK_PK primary key (LOCK_KEY, REGION)
 );
@@ -38,7 +38,7 @@ CREATE SEQUENCE INT_MESSAGE_SEQ START WITH 1 INCREMENT BY 1 NOCACHE NOCYCLE;
 
 CREATE TABLE INT_CHANNEL_MESSAGE (
 	MESSAGE_ID CHAR(36) NOT NULL,
-	GROUP_KEY CHAR(36) NOT NULL,
+	GROUP_KEY VARCHAR2(36) NOT NULL,
 	CREATED_DATE NUMBER(19,0) NOT NULL,
 	MESSAGE_PRIORITY NUMBER(19,0),
 	MESSAGE_SEQUENCE NUMBER(19,0) NOT NULL ,
@@ -51,7 +51,6 @@ CREATE INDEX INT_CHANNEL_MSG_DELETE_IDX ON INT_CHANNEL_MESSAGE (REGION, GROUP_KE
 -- This is only needed if the message group store property 'priorityEnabled' is true
 -- CREATE UNIQUE INDEX INT_CHANNEL_MSG_PRIORITY_IDX ON INT_CHANNEL_MESSAGE (REGION, GROUP_KEY, MESSAGE_PRIORITY DESC, CREATED_DATE, MESSAGE_SEQUENCE);
 
-
 CREATE TABLE INT_METADATA_STORE  (
 	METADATA_KEY VARCHAR2(255) NOT NULL,
 	METADATA_VALUE VARCHAR2(4000),