* Copy cert files from classpath to file-system If `ssl.truststore.location` and `ssl.keystore.location` are provided as classpath resources, convert them to absolute paths on the filesystem. This is because of a restriction in the Kafka client in which it does not allow certificates to be read from the classpath. See these issues for more details: https://issues.apache.org/jira/browse/KAFKA-7685 https://cwiki.apache.org/confluence/display/KAFKA/KIP-398%3A+Support+reading+trust+store+from+classpath This commit allows the Spring Cloud Stream application to provide the cert files as classpath: reosources, but the binder internally move them to a locations on the local filesystem and then use that absolute path as the value for cert locations. Adding properties for optional paths to move the files to. If no values are provided for these properties, then use the system's /tmp directory. Adding tests and docs. Resolves https://github.com/spring-cloud/spring-cloud-stream-binder-kafka/issues/985 * Addressing PR review comments * Addressing further PR review comments * Consolidate keystore/truststore filesystem locations into a single property * Addressing PR review