protected T readObjectFromString(final String jsonString) {
        try {
            LOGGER.trace("Attempting to parse [{}]", jsonString);
            return getTypeReader().readValue(jsonString);
        } catch (final Exception e) {
            LOGGER.error("Cannot read/parse [{}] to deserialize into type [{}]. This may be caused "
                    + "in the absence of a configuration/support module that knows how to interpret the fragment, "
                    + "specially if the fragment describes a CAS registered service definition. "
                    + "Internal parsing error is [{}]",
                DigestUtils.abbreviate(jsonString), getTypeToSerialize(), e.getMessage());
            LOGGER.debug(e.getMessage(), e);
        }
        return null;
    }
Gets object mapper and builds on if uninitialized.

@return the object mapper
core/cas-server-core-util-api/src/main/java/org/apereo/cas/util/serialization/BaseJacksonSerializer.java