There is a change to the third party license file starting in JDK 9.
Please refer to this bug:
Snips from the bug:
The JDK source code includes dozens of third party libraries, each subject
to license. Historically, third party licenses from across the JDK were
aggregated by hand into a single file, `THIRD_PARTY_README`, at the end
of a JDK release.
To simplify maintenance, we propose to drop the aggregated
`THIRD_PARTY_README` file from each JDK repository. To enhance precision,
we propose to store each third party notices in the module that contains
the third party code subject to the license.
Under this scheme, the source layout is:
The `legal` directory contains one file for each third party
library in the module, for example,
src/java.base/share/legal/asm.md unicode.md zlib.md
So have a look for the *.md files that included with the jdk-9-ea+168_linux-x64_bin.tar.gz you downloaded.