with version 2.2 of the plugin all works great, with the versione 2.3 some jobs have this issue
Starting Aggregate Test Results Action
Total Jenkins jobs found 183 and Aggregator has resolved successfully 9/9
Collect data
ERROR Error get details for job 'CI-xxxx-CI-xxxxxx-f-SERVICE-LOAD' Unexpected character ('<' (code 60)): expected a valid value (JSON String, Number, Array, Object or token 'null', 'true' or 'false')
at [Source: REDACTED (`StreamReadFeature.INCLUDE_SOURCE_IN_LOCATION` disabled); line: 3, column: 3] stacktrace com.fasterxml.jackson.core.JsonParseException: Unexpected character ('<' (code 60)): expected a valid value (JSON String, Number, Array, Object or token 'null', 'true' or 'false')
at [Source: REDACTED (`StreamReadFeature.INCLUDE_SOURCE_IN_LOCATION` disabled); line: 3, column: 3]
at PluginClassLoader for jackson2-api//com.fasterxml.jackson.core.JsonParser._constructReadException(JsonParser.java:2643)
at PluginClassLoader for jackson2-api//com.fasterxml.jackson.core.base.ParserMinimalBase._reportUnexpectedChar(ParserMinimalBase.java:685)
at PluginClassLoader for jackson2-api//com.fasterxml.jackson.core.json.ReaderBasedJsonParser._handleOddValue(ReaderBasedJsonParser.java:2055)
at PluginClassLoader for jackson2-api//com.fasterxml.jackson.core.json.ReaderBasedJsonParser.nextToken(ReaderBasedJsonParser.java:780)
at PluginClassLoader for jackson2-api//com.fasterxml.jackson.databind.ObjectMapper._initForReading(ObjectMapper.java:4992)
at PluginClassLoader for jackson2-api//com.fasterxml.jackson.databind.ObjectMapper._readMapAndClose(ObjectMapper.java:4898)
at PluginClassLoader for jackson2-api//com.fasterxml.jackson.databind.ObjectMapper.readValue(ObjectMapper.java:3848)
at PluginClassLoader for jackson2-api//com.fasterxml.jackson.databind.ObjectMapper.readValue(ObjectMapper.java:3816)
at PluginClassLoader for test-results-aggregator//com.jenkins.testresultsaggregator.actions.Collector.getData(Collector.java:468)
at PluginClassLoader for test-results-aggregator//com.jenkins.testresultsaggregator.actions.Collector.getDetailsMode(Collector.java:160)
at PluginClassLoader for test-results-aggregator//com.jenkins.testresultsaggregator.actions.Collector.getDetails(Collector.java:138)
at PluginClassLoader for test-results-aggregator//com.jenkins.testresultsaggregator.actions.Collector$ReportThread.run(Collector.java:293)

Job 'CI-xxxx-CI-xxxxxx-f-SERVICE-LOAD' found NOT_FOUND