contents in browsermobproxy is coming as null most of the times while doing addResponseFilter with java - httpresponse

Question

I am using
'net.lightbody.bmp:browsermob-core:2.1.5'
'org.seleniumhq.selenium:selenium-java:3.141.59'
In the below code, I am trying to override the response content . While I am using the debugging, it's going inside the if block but because contents is NULL ( 19 out of 20 times its null) , so it gives null pointer exception.
But response and messageInfo is coming fine.
ProxyUtils.getInstance().getProxy().addResponseFilter((response, contents, messageInfo) -> {
if (messageInfo.getOriginalUrl().contains("/getproduct")) {
contents.setTextContents("{\"data\":{\"items\":[]}}");
}
});
Exception:-
[LittleProxy-0-ProxyToServerWorker-3] WARN
net.lightbody.bmp.filters.BrowserMobHttpFilterChain - Filter in
filter chain threw exception. Filter method may have been aborted.
java.lang.NullPointerException
at net.lightbody.bmp.filters.ResponseFilterAdapter.serverToProxyResponse(ResponseFilterAdapter.java:49)
at net.lightbody.bmp.filters.BrowserMobHttpFilterChain.serverToProxyResponse(BrowserMobHttpFilterChain.java:123)
at org.littleshoot.proxy.impl.ClientToProxyConnection.respond(ClientToProxyConnection.java:434)
at org.littleshoot.proxy.impl.ProxyToServerConnection.respondWith(ProxyToServerConnection.java:519)
at org.littleshoot.proxy.impl.ProxyToServerConnection.readHTTPInitial(ProxyToServerConnection.java:238)
at org.littleshoot.proxy.impl.ProxyToServerConnection.readHTTPInitial(ProxyToServerConnection.java:77)
at org.littleshoot.proxy.impl.ProxyConnection.readHTTP(ProxyConnection.java:135)
at org.littleshoot.proxy.impl.ProxyConnection.read(ProxyConnection.java:120)
at org.littleshoot.proxy.impl.ProxyToServerConnection.read(ProxyToServerConnection.java:214)
at org.littleshoot.proxy.impl.ProxyConnection.channelRead0(ProxyConnection.java:587)
at io.netty.channel.SimpleChannelInboundHandler.channelRead(SimpleChannelInboundHandler.java:105)
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:356)
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:342)
at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:335)
at io.netty.handler.timeout.IdleStateHandler.channelRead(IdleStateHandler.java:286)
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:356)
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:342)
at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:335)
at io.netty.channel.ChannelInboundHandlerAdapter.channelRead(ChannelInboundHandlerAdapter.java:86)
at org.littleshoot.proxy.impl.ProxyConnection$ResponseReadMonitor.channelRead(ProxyConnection.java:738)
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:356)
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:342)
at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:335)
at io.netty.handler.codec.ByteToMessageDecoder.fireChannelRead(ByteToMessageDecoder.java:312)
at io.netty.handler.codec.ByteToMessageDecoder.fireChannelRead(ByteToMessageDecoder.java:299)
at io.netty.handler.codec.ByteToMessageDecoder.callDecode(ByteToMessageDecoder.java:415)
at io.netty.handler.codec.ByteToMessageDecoder.channelRead(ByteToMessageDecoder.java:267)
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:356)
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:342)
at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:335)
at io.netty.channel.ChannelInboundHandlerAdapter.channelRead(ChannelInboundHandlerAdapter.java:86)
at org.littleshoot.proxy.impl.ProxyConnection$BytesReadMonitor.channelRead(ProxyConnection.java:692)
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:356)
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:342)
at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:335)
at io.netty.handler.ssl.SslHandler.unwrap(SslHandler.java:1296)
at io.netty.handler.ssl.SslHandler.decodeJdkCompatible(SslHandler.java:1087)
at io.netty.handler.ssl.SslHandler.decode(SslHandler.java:1122)
at io.netty.handler.codec.ByteToMessageDecoder.decodeRemovalReentryProtection(ByteToMessageDecoder.java:491)
at io.netty.handler.codec.ByteToMessageDecoder.callDecode(ByteToMessageDecoder.java:430)
at io.netty.handler.codec.ByteToMessageDecoder.channelRead(ByteToMessageDecoder.java:267)
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:356)
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:342)
at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:335)
at io.netty.channel.DefaultChannelPipeline$HeadContext.channelRead(DefaultChannelPipeline.java:1302)
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:356)
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:342)
at io.netty.channel.DefaultChannelPipeline.fireChannelRead(DefaultChannelPipeline.java:919)
at io.netty.channel.nio.AbstractNioByteChannel$NioByteUnsafe.read(AbstractNioByteChannel.java:131)
at io.netty.channel.nio.NioEventLoop.processSelectedKey(NioEventLoop.java:646)
at io.netty.channel.nio.NioEventLoop.processSelectedKeysOptimized(NioEventLoop.java:581)
at io.netty.channel.nio.NioEventLoop.processSelectedKeys(NioEventLoop.java:498)
at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:460)
at io.netty.util.concurrent.SingleThreadEventExecutor$2.run(SingleThreadEventExecutor.java:131)
at java.lang.Thread.run(Thread.java:748)