Add directive in readme.java.md to make redisConfiguration.additonalProperties as string to string map (#20715)

* add directive in readme.java.md to make additonalProperties in redisConfiguration as Map<String, String>

* clean up redis/resource-manager/readme.md

Author: haolingdong-msft

specification/redis/resource-manager/readme.java.md

@@ -0,0 +1,11 @@
+## Java
+
+These settings apply only when `--java` is specified on the command line.
+
+``` yaml $(java)
+directive:
+  - from: redis.json
+    where: $.definitions.RedisCommonProperties.properties.redisConfiguration.additionalProperties
+    transform: $['type'] = "string"
+    reason: additonal properties should be string to string map
+```

specification/redis/resource-manager/readme.md

@@ -169,51 +169,7 @@ See configuration in [readme.go.md](./readme.go.md)
 
 ## Java
 
-These settings apply only when `--java` is specified on the command line.
-Please also specify `--azure-libraries-for-java-folder=<path to the root directory of your azure-libraries-for-java clone>`.
-
-``` yaml $(java)
-azure-arm: true
-fluent: true
-namespace: com.microsoft.azure.management.redis
-license-header: MICROSOFT_MIT_NO_CODEGEN
-payload-flattening-threshold: 1
-output-folder: $(azure-libraries-for-java-folder)/azure-mgmt-redis
-```
-
-### Java multi-api
-
-``` yaml $(java) && $(multiapi)
-batch:
-  - tag: package-2018-03
-  - tag: package-2017-10
-```
-
-### Tag: package-2018-03 and java
-
-These settings apply only when `--tag=package-2018-03 --java` is specified on the command line.
-Please also specify `--azure-libraries-for-java-folder=<path to the root directory of your azure-sdk-for-java clone>`.
-
-``` yaml $(tag) == 'package-2018-03' && $(java) && $(multiapi)
-java:
-  namespace: com.microsoft.azure.management.redis.v2018_03_01
-  output-folder: $(azure-libraries-for-java-folder)/sdk/redis/mgmt-v2018_03_01
-regenerate-manager: true
-generate-interface: true
-```
-
-### Tag: package-2017-10 and java
-
-These settings apply only when `--tag=package-2017-10 --java` is specified on the command line.
-Please also specify `--azure-libraries-for-java-folder=<path to the root directory of your azure-sdk-for-java clone>`.
-
-``` yaml $(tag) == 'package-2017-10' && $(java) && $(multiapi)
-java:
-  namespace: com.microsoft.azure.management.redis.v2017_10_01
-  output-folder: $(azure-libraries-for-java-folder)/sdk/redis/mgmt-v2017_10_01
-regenerate-manager: true
-generate-interface: true
-```
+See configuration in [readme.java.md](./readme.java.md)
 
 # Validation