logstash-logback-encoder display stacktrace in multiple lines

I did sth like

<provider class="com.ac.log.CustomStackTraceJsonProvider">    <throwableConverter class="net.logstash.logback.stacktrace.ShortenedThrowableConverter">        <maxDepthPerThrowable>full</maxDepthPerThrowable>        <maxLength>full</maxLength>        <shortenedClassNameLength>20</shortenedClassNameLength>        <exclusions>${STE_EXCLUSIONS}</exclusions>        <rootCauseFirst>true</rootCauseFirst>    </throwableConverter></provider>

And the class looks like

import java.io.IOException;import java.util.LinkedHashMap;import java.util.Map;import com.fasterxml.jackson.core.JsonGenerator;import ch.qos.logback.classic.spi.ILoggingEvent;import ch.qos.logback.classic.spi.IThrowableProxy;import net.logstash.logback.composite.JsonWritingUtils;import net.logstash.logback.composite.loggingevent.StackTraceJsonProvider;public class CustomStackTraceJsonProvider extends StackTraceJsonProvider {  public CustomStackTraceJsonProvider() {    super();  }  @Override  public void writeTo(JsonGenerator generator, ILoggingEvent event) throws IOException {    IThrowableProxy throwableProxy = event.getThrowableProxy();    if (throwableProxy != null) {      String msg = getThrowableConverter().convert(event);      String[] lines = msg.split("\\n\\t");      Map<String, String> lineMap = new LinkedHashMap<>();      for(int i = 0; i < lines.length; i++){        lineMap.put(String.valueOf(i+1), lines[i]);      }      JsonWritingUtils.writeMapStringFields(generator, getFieldName(), lineMap);    }  }}

which gives an output in the format

{  l_t : "2018-04-14T20:00:25.066-07:00",  l_l : "ERROR",  l_m : "Error while validating field existence",  service : "com.ac.api.client.product.ProductService",  method : "fetchProduct",  value : "p-j0ednf7f6wd8l6rss",  l_th : "http-nio-8080-exec-5",  stack_hash : "26c1547b",  l_c : "com.ac.core.validation.ExistsByStringFieldValidator:isValid:34",  stack_trace : {    1 : "c.i.c.a.c.e.RemoteServiceException: error code: 1002, user msg: remote.service.objectNotFound, parameters: [(identifier: p-j0ednf7f6wd8l6rss)]",    2 : "at c.i.c.a.c.p.ProductServiceImpl.toProduct(ProductServiceImpl.java:69)",    3 : "at c.i.c.a.c.p.ProductServiceImpl.fetchProductInternal(ProductServiceImpl.java:44)",    4 : "at c.i.c.a.c.p.ProductServiceImpl.fetchProduct(ProductServiceImpl.java:33)",    5 : "at c.i.c.a.c.p.ProductServiceImpl$$FastClassBySpringCGLIB$$5ee58445.invoke(<generated>)",    6 : "at o.s.c.p.MethodProxy.invoke(MethodProxy.java:204)",    7 : "at o.s.a.f.CglibAopProxy$CglibMethodInvocation.invokeJoinpoint(CglibAopProxy.java:738)",    8 : "at o.s.a.f.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:157)",    9 : "at o.s.c.j.i.JCacheInterceptor$1.invoke(JCacheInterceptor.java:52)",    10 : "at o.s.c.j.i.JCacheAspectSupport.invokeOperation(JCacheAspectSupport.java:153)",    11 : "at o.s.c.j.i.JCacheAspectSupport$CacheOperationInvokerAdapter.invoke(JCacheAspectSupport.java:167)",    12 : "at o.s.c.j.i.CacheResultInterceptor.invoke(CacheResultInterceptor.java:62)",    13 : "at o.s.c.j.i.JCacheAspectSupport.execute(JCacheAspectSupport.java:123)",    14 : "at o.s.c.j.i.JCacheAspectSupport.execute(JCacheAspectSupport.java:102)",    15 : "at o.s.c.j.i.JCacheInterceptor.invoke(JCacheInterceptor.java:61)",    16 : "at o.s.a.f.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)",    17 : "at o.s.a.f.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:673)",    18 : "at c.i.c.a.c.p.ProductServiceImpl$$EnhancerBySpringCGLIB$$f315262.fetchProduct(<generated>)",    19 : "... 124 common frames omitted\nWrapped by: j.l.r.InvocationTargetException: null",    20 : "at s.r.NativeMethodAccessorImpl.invoke0(NativeMethodAccessorImpl.java)",    21 : "at s.r.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)",    22 : "at s.r.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)",    23 : "at j.l.reflect.Method.invoke(Method.java:498)",    24 : "at c.i.c.c.v.ExistsByStringFieldValidator.isValid(ExistsByStringFieldValidator.java:29)",    25 : "at c.i.c.c.v.ExistsByStringFieldValidator.isValid(ExistsByStringFieldValidator.java:12)",    26 : "at o.h.v.i.e.c.ConstraintTree.validateSingleConstraint(ConstraintTree.java:448)",    27 : "at o.h.v.i.e.c.ConstraintTree.validateConstraints(ConstraintTree.java:127)",    28 : "at o.h.v.i.e.c.ConstraintTree.validateComposingConstraints(ConstraintTree.java:398)",    29 : "at o.h.v.i.e.c.ConstraintTree.validateConstraints(ConstraintTree.java:98)",    30 : "at o.h.v.i.e.c.ConstraintTree.validateConstraints(ConstraintTree.java:87)",    31 : "at o.h.v.i.m.c.MetaConstraint.validateConstraint(MetaConstraint.java:73)",    32 : "at o.h.v.i.e.ValidatorImpl.validateMetaConstraint(ValidatorImpl.java:621)",    33 : "at o.h.v.i.e.ValidatorImpl.validateConstraint(ValidatorImpl.java:584)",    34 : "at o.h.v.i.e.ValidatorImpl.validateConstraintsForSingleDefaultGroupElement(ValidatorImpl.java:528)",    35 : "at o.h.v.i.e.ValidatorImpl.validateConstraintsForDefaultGroup(ValidatorImpl.java:496)",    36 : "at o.h.v.i.e.ValidatorImpl.validateConstraintsForCurrentGroup(ValidatorImpl.java:461)",    37 : "at o.h.v.i.e.ValidatorImpl.validateInContext(ValidatorImpl.java:411)",    38 : "at o.h.v.i.e.ValidatorImpl.validateCascadedConstraint(ValidatorImpl.java:762)",    39 : "at o.h.v.i.e.ValidatorImpl.validateCascadedConstraints(ValidatorImpl.java:685)",    40 : "at o.h.v.i.e.ValidatorImpl.validateParametersInContext(ValidatorImpl.java:1126)",    41 : "at o.h.v.i.e.ValidatorImpl.validateParameters(ValidatorImpl.java:302)",    42 : "at o.h.v.i.e.ValidatorImpl.validateParameters(ValidatorImpl.java:256)",    43 : "at s.r.NativeMethodAccessorImpl.invoke0(NativeMethodAccessorImpl.java)",    44 : "at s.r.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)",    45 : "... 99 frames truncated\n"  }}