Apache http client with https proxy - apache-httpcomponents

Question

I am using Apache HTTP Components HttpClient using the following code.
HttpAsyncClientBuilder builder = HttpAsyncClients.custom();
builder.setConnectionManager(manager);
builder.setRoutePlanner(planner)
.setDefaultCredentialsProvider(provider);
return builder.build();
And,
return new DefaultProxyRoutePlanner(new HttpHost("https", proxyHost, proxyPort));
The flow is like below,
http client -> https proxy(with auth) -> https endpoint
The code makes a successful connection to the proxy but ends up with the below TLS error.
.c.h.i.a.InternalAbstractHttpAsyncClient : ex-0000000001 preparing request execution
o.a.h.c.h.p.RequestAddCookies : ex-0000000001 Cookie spec selected: strict
o.a.h.c.h.p.RequestAuthCache : ex-0000000001 Re-using cached 'Basic' auth scheme for https://proxy.host:3128
o.a.h.c.h.i.a.AsyncProtocolExec : ex-0000000001 target auth state: UNCHALLENGED
o.a.h.c.h.i.a.AsyncConnectExec : ex-0000000001 acquiring connection with route {tls}->https://proxy.host:3128->https://api.host:443
o.a.h.c.h.i.a.InternalHttpAsyncClient : ex-0000000001 acquiring endpoint (3 MINUTES)
.i.n.PoolingAsyncClientConnectionManager : ex-0000000001 endpoint lease request (3 MINUTES) [route: {tls}->https://proxy.host:3128->https://api.host:443][total available: 0; route allocated: 0 of 5; total allocated: 0 of 25]
.i.n.PoolingAsyncClientConnectionManager : ex-0000000001 endpoint leased [route: {tls}->https://proxy.host:3128->https://api.host:443][total available: 0; route allocated: 1 of 5; total allocated: 1 of 25]
.i.n.PoolingAsyncClientConnectionManager : ex-0000000001 acquired ep-0000000000
o.a.h.c.h.i.a.InternalHttpAsyncClient : ex-0000000001 acquired endpoint ep-0000000000
o.a.h.c.h.i.a.InternalHttpAsyncClient : ep-0000000000 connecting endpoint (3 MINUTES)
.i.n.PoolingAsyncClientConnectionManager : ep-0000000000 connecting endpoint to https://proxy.host:3128 (3 MINUTES)
.a.h.c.h.i.n.MultihomeIOSessionRequester : https://proxy.host:3128 resolving remote address
.a.h.c.h.i.n.MultihomeIOSessionRequester : https://proxy.host:3128 resolved to [proxy.host/XX.XX.XX.XX, proxy.host/10.XX.XX.88]
.a.h.c.h.i.n.MultihomeIOSessionRequester : https://proxy.host:3128 connecting null to proxy.host/XX.XX.XX.XX:3128 (3 MINUTES)
o.a.h.c.r.IOSessionImpl : c-0000000000[ACTIVE][rc:c] protocol upgrade class org.apache.hc.core5.http2.impl.nio.ClientHttpProtocolNegotiator
.a.h.c.h.i.n.MultihomeIOSessionRequester : https://proxy.host:3128 connected c-0000000000 /XXX.XX.XX.XXX:44774->proxy.host/XX.XX.XX.XX:3128
.i.n.DefaultManagedAsyncClientConnection : c-0000000000 start TLS
.i.n.PoolingAsyncClientConnectionManager : ep-0000000000 connected c-0000000000
o.a.h.c.h.i.a.InternalHttpAsyncClient : ep-0000000000 endpoint connected
o.a.h.c.h.i.a.AsyncConnectExec : ex-0000000001 connected to proxy
o.a.h.c.h.i.a.AsyncConnectExec : ex-0000000001 create tunnel
o.a.h.c.h.i.a.HttpAsyncMainClientExec : ex-0000000001 executing CONNECT api.host:443 HTTP/1.1
o.a.h.c.h.i.a.InternalHttpAsyncClient : ep-0000000000 start execution ex-0000000001
.i.n.PoolingAsyncClientConnectionManager : ep-0000000000 executing exchange ex-0000000001 over c-0000000000
.i.n.DefaultManagedAsyncClientConnection : c-0000000000 RequestExecutionCommand with NORMAL priority
o.a.h.c.r.s.SSLIOSession : c-0000000000[ACTIVE][rwc:c][ACTIVE][rw][NOT_HANDSHAKING][0][0][0] Enqueued RequestExecutionCommand with priority IMMEDIATE
o.a.h.c.r.s.SSLIOSession : c-0000000000[ACTIVE][rw:c][ACTIVE][rw][NOT_HANDSHAKING][0][0][0] Event cleared [c]
o.a.h.c.r.s.SSLIOSession : c-0000000000[ACTIVE][r:r][ACTIVE][rw][NOT_HANDSHAKING][0][0][0] protocol upgrade class org.apache.hc.core5.http.impl.nio.ClientHttp1IOEventHandler
o.a.h.c.h.i.a.HttpAsyncMainClientExec : ex-0000000001 send request CONNECT api.host:443 HTTP/1.1, null entity
o.a.h.c.h.headers : c-0000000000 >> CONNECT api.host:443 HTTP/1.1
o.a.h.c.h.headers : c-0000000000 >> Host: api.host:443
o.a.h.c.h.headers : c-0000000000 >> User-Agent: Apache-HttpAsyncClient/5.1.3 (Java/17.0.4)
o.a.h.c.h.headers : c-0000000000 >> Proxy-Authorization: Basic <token>
o.a.h.c.r.s.SSLIOSession : c-0000000000[ACTIVE][r:r][ACTIVE][rw][NOT_HANDSHAKING][0][0][347] 318 bytes written
.
.
.
o.a.h.c.r.s.SSLIOSession : c-0000000000[ACTIVE][r:r][ACTIVE][r][NOT_HANDSHAKING][68][39][0] 0 bytes read
o.a.h.c.h.headers : c-0000000000 << HTTP/1.1 200 Connection established
o.a.h.c.h.i.a.HttpAsyncMainClientExec : ex-0000000001 consume response HTTP/1.1 200 Connection established, null entity
o.a.h.c.h.i.a.AsyncConnectExec : ex-0000000001 tunnel to target created
o.a.h.c.h.i.a.InternalHttpAsyncClient : ep-0000000000 upgrading endpoint
.i.n.DefaultManagedAsyncClientConnection : c-0000000000 start TLS
o.a.h.c.h.i.a.HttpAsyncMainClientExec : ex-0000000001 execution failed: TLS already activated
.c.h.i.a.InternalAbstractHttpAsyncClient : ex-0000000001 request failed: TLS already activated
.i.n.PoolingAsyncClientConnectionManager : ep-0000000000 close IMMEDIATE
.i.n.DefaultManagedAsyncClientConnection : c-0000000000 Shutdown connection IMMEDIATE
o.a.h.c.r.s.SSLIOSession : c-0000000000[ACTIVE][r:r][ACTIVE][r][NOT_HANDSHAKING][0][0][0] Close IMMEDIATE
o.a.h.c.h.i.a.InternalHttpAsyncClient : ep-0000000000 endpoint closed
o.a.h.c.h.i.a.InternalHttpAsyncClient : ep-0000000000 discarding endpoint
.i.n.PoolingAsyncClientConnectionManager : ep-0000000000 releasing endpoint
.i.n.PoolingAsyncClientConnectionManager : ep-0000000000 connection released [route: {tls}->https://proxy.host:3128->https://api.host:443][total available:0; route allocated: 0 of 5; total allocated: 0 of 25]
Any pointers on whats going on here and how to go about the above flow?