Solved the issue. Stored Decimal value successfully. I have done two mistakes.
1 ) LineString can only store Points datatype (Not the decimal values or coordinates). Corrected syntax follows.
INSERT INTO HIBERNATE_SPATIAL
(PRD_GEO_REGION_ID,OWNER_ID,GEO_REGION_NAME,GEO_REGION_DESCRIPTION,GEO_REGION_DEFINITION)
VALUES (8,1,'POLYGON8','SHAPE8',Polygon(LineString(POINT(10.12345612341243,11.12345612341234)),LineString(POINT(10.34512341246,11.4123423456)),LineString(POINT(10.31423424456,11.34123423456)),LineString(POINT(10.341234256,11.3412342456)),LineString(POINT(10.11423423456,11.123424))));
2 ) If it is a polygon shape. The shape has to be closed ( Starting and Ending point should be the same ). That was the problem.
WORKING QUERY
INSERT INTO HIBERNATE_SPATIAL
(PRD_GEO_REGION_ID,OWNER_ID,GEO_REGION_NAME,GEO_REGION_DESCRIPTION,GEO_REGION_DEFINITION)
VALUES (8,1,'POLYGON8','SHAPE8',Polygon(LineString(POINT(10.12345612341243,11.12345612341234)),LineString(POINT(10.34512341246,11.4123423456)),LineString(POINT(10.31423424456,11.34123423456)),LineString(POINT(10.341234256,11.3412342456)),LineString(POINT(10.12345612341243,11.12345612341234))));