Error occurs when trying to get protocol parameter on testnet

[EV6999]

Describe the bug
The following Error occurs when trying to get protocol parameter on testnet. No error occurs at mainnnet.

`2022-07-12 13:38:08.985 ERROR 23527 --- [nio-3001-exec-7] o.a.c.c.C.[.[.[/].[dispatcherServlet]    : Servlet.service() for servlet [dispatcherServlet] in context with path [] threw exception [Request processing failed; nested exception is com.apollographql.apollo.exception.ApolloHttpException: HTTP 400 ] with root cause

com.apollographql.apollo.exception.ApolloHttpException: HTTP 400 
	at com.apollographql.apollo.internal.interceptor.ApolloParseInterceptor.parse(ApolloParseInterceptor.java:108) ~[apollo-runtime-2.5.9.jar:2.5.9]
	at com.apollographql.apollo.internal.interceptor.ApolloParseInterceptor$1.onResponse(ApolloParseInterceptor.java:53) ~[apollo-runtime-2.5.9.jar:2.5.9]
	at com.apollographql.apollo.internal.interceptor.ApolloServerInterceptor$executeHttpCall$1.onResponse(ApolloServerInterceptor.kt:114) ~[apollo-runtime-2.5.9.jar:2.5.9]
	at okhttp3.internal.connection.RealCall$AsyncCall.run(RealCall.kt:519) ~[okhttp-4.9.2.jar:na]
	at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128) ~[na:na]
	at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628) ~[na:na]
	at java.base/java.lang.Thread.run(Thread.java:829) ~[na:na]
	Suppressed: java.lang.Exception: #block terminated with an error
		at reactor.core.publisher.BlockingSingleSubscriber.blockingGet(BlockingSingleSubscriber.java:93) ~[reactor-core-3.2.2.RELEASE.jar:3.2.2.RELEASE]
		at reactor.core.publisher.Mono.block(Mono.java:1475) ~[reactor-core-3.2.2.RELEASE.jar:3.2.2.RELEASE]
		at com.bloxbean.cardano.client.backend.gql.BaseGqlService.execute(BaseGqlService.java:81) ~[cardano-client-backend-gql-internal-rc4-0.1.5-SNAPSHOT.jar:na]
		at com.bloxbean.cardano.client.backend.gql.GqlEpochService.getProtocolParameters(GqlEpochService.java:82) ~[cardano-client-backend-gql-internal-rc4-0.1.5-SNAPSHOT.jar:na]
		at com.bloxbean.cardano.client.backend.gql.GqlEpochService.getProtocolParameters(GqlEpochService.java:135) ~[cardano-client-backend-gql-internal-rc4-0.1.5-SNAPSHOT.jar:na]`

To Reproduce
Steps to reproduce the behavior:

1. Use getProtocolParameters() of EpochService

Expected behavior
Get correct result of Protocol Parameters

Screenshots
If applicable, add screenshots to help explain your problem.

Desktop (please complete the following information):

• Ubuntu 22.04

[EV6999]

Sorry. Actually found the reason. Thanks.